Opinion by Judge HAWKINS; Dissent by Judge BERZON.
We primarily consider whether a jury instruction impermissibly relieved the government of its burden to prove beyond a reasonable doubt that the defendant used a “dangerous weapon” and whether any error in the instruction was harmless. A panel of our court held that the jury instruction was not defective and affirmed the defendant’s conviction. United States v. Smith, 520 F.3d 1097 (9th Cir.2008). We subsequently granted rehearing en banc.
Although we hold there was a “reasonable likelihood” the trial judge’s instructions “misled” the jury to think they did not have to determine beyond a reasonable doubt that the defendant used a dangerous weapon, see Middleton v. McNeil, 541 U.S. 433, 437, 124 S.Ct. 1830, 158 L.Ed.2d 701 (2004) (per curiam), we nevertheless affirm Smith’s conviction because we “conclude that it is ‘clear beyond a reasonable doubt that a rational jury would have found the defendant guilty absent the error.’ ” United States v. Gracidas-Ulibarry, 231 F.3d 1188, 1197 (9th Cir.2000) (en banc) (quoting Neder v. United States, 527 U.S. 1, 18, 119 S.Ct. 1827, 144 L.Ed.2d 35 (1999)).
Smith also challenges his sentence. Concluding that the district court erred in delegating its statutory duties and applying the Sentencing Guidelines to the facts of this case, we vacate Smith’s sentence and remand for further sentencing proceedings consistent with this Opinion.
I.
A.
Prison officials at the federal penitentiary in Lompoc, California, found Charles Helem holding George Jeffries from behind while Malik Smith was stabbing Jef-fries with a prison-made knife. The knife used in the assault was a flat, six-inch-long “shank” fashioned from melted plastic dishware. It was hard and sharpened to a point. Although the prison-made knife broke in two under the force of the stabbing, Smith continued to strike Jeffries with one of the pieces until Jeffries broke away.
After the' altercation, the three inmates were examined by Reynaldo Nísperos, a *937physician’s assistant at the prison. Níspe-ros — a twenty-year veteran of the Bureau of Prisons who has treated between fifty and one hundred prison stabbings — found no injuries on Helem and only minor abrasions on Smith’s hands and lower lip. His examination of Jeffries, however, revealed “very extensive injuries],” including: a “ten centimeters,” “full-skin thick” laceration on Jeffries’s right eyelid; an “eight centimeters full-skin thickness laceration” on the left parietal region of his head; a third, less serious laceration; superficial abrasions on his neck and right knee; and several “abrasions and lacerations” of varying sizes on his lower back. Nísperos provided first aid to both Smith and Jef-fries for their injuries.
After the incident, the prison punished Smith for assault and possession of a sharpened instrument, imposing 120 days of disciplinary segregation and deducting 360 visitor days and 80 days of good conduct time. Smith was subsequently released from prison in 2002.
B.
After his release, Smith was charged in connection with the prison fight with “Assault with intent to commit murder,” in violation of 18 U.S.C. § 113(a)(1), and “Assault with a dangerous weapon, with intent to do bodily harm,” in violation of 18 U.S.C. § 113(a)(3). At trial, Lieutenant Jaime Bengford testified that the prison-made knife had been made by accumulating and melting down plastic meal trays to create a “weapon.” Testifying as a medical expert,1 Nísperos explained to the jury the severity of Jeffries’s injuries, describing them as “very extensive” and detailing the locations of the specific wounds. When subsequently asked whether, “in your opinion, based on your experience, if someone was stabbed in a vital organ with that prison-made knife, could that injury be fatal,” Nísperos testified that the prison-made knife “could cause very fatal injuries.” Smith never challenged, on cross-examination or at any other time before the jury, Nisperos’s conclusions that the prison-made knife did cause “very extensive” injuries, including a skin-deep laceration on Jeffries’s eyelid, or that it could have caused fatal injuries.
At the conclusion of trial, the court instructed the jury on assault with intent to commit murder, assault with a dangerous weapon, and the lesser-included offense of simple assault. Tracking this circuit’s then-current Model Criminal Jury Instruction 8.5, the trial court instructed the jury on assault with a dangerous weapon as follows: *938(Emphasis added.) Smith objected to the instructions, contending that the third element usurped the jury’s role as finder of fact as to whether the knife qualified as a “dangerous weapon.”
*937The defendant is charged in Count 2 of the indictment with assault with a dangerous weapon, in violation of Section 113(a)(3) of Title 18 of the United States Code.
In order for the defendant to be found guilty of that charge, the Government must prove each of the following elements beyond a reasonable doubt: First, the defendant intentionally struck or wounded George Jeffries; second, the defendant acted with the specific intent to do bodily harm to George Jeffries; and, third, the defendant used a prison-made knife.
A prison-made knife is a dangerous weapon if it is used in a way that is capable of causing death or serious bodily injury.2
*938The jury acquitted Smith of attempted murder but convicted him of assault with a dangerous weapon. The court sentenced Smith to 100 months in prison to run consecutively with his undischarged term of imprisonment, followed by three years of supervised release. Smith timely appealed, arguing in part that the district court’s jury instruction had improperly charged the jury to find only that Smith committed assault with a prison-made knife, rather than assault with a dangerous weapon, effectively relieving the government of the burden to prove the prison-made knife was a dangerous weapon.
II.
A.
We review de novo the legal sufficiency of jury instructions. United States v. Romo-Romo, 246 F.3d 1272, 1274 (9th Cir.2001).
B.
“[T]he Due Process Clause of the Fourteenth Amendment requires that the prosecution prove beyond a reasonable doubt every fact necessary to establish each element of the crimes charged.” Mejia v. Garcia, 534 F.3d 1036, 1042 (9th Cir.2008) (citing In re Winship, 397 U.S. 358, 364, 90 S.Ct. 1068, 25 L.Ed.2d 368 (1970)), cert. denied, — U.S. -, 129 S.Ct. 941, 173 L.Ed.2d 141 (2009). A defendant is therefore deprived of constitutional due process when the jury is not properly instructed that the government bears the burden of proving guilt beyond a reasonable doubt on each element of the crime. Middleton, 541 U.S. at 437, 124 S.Ct. 1830. Here, the trial court stated that to support a conviction, the jury needed to find “the defendant used a prison-made knife.” Although the court then defined under what circumstances a prison-made knife constitutes a dangerous weapon, the instructions did not unambiguously require the jury to find the prison-made knife was, in fact, a dangerous weapon. We therefore conclude there is a “reasonable likelihood” the trial judge’s instructions “misled” the jury to believe they did not have to determine beyond a reasonable doubt that the prison-made knife was a dangerous weapon.
Not all constitutional errors require reversal, however. The Supreme Court has specifically recognized that omitting an offense element from a jury instruction is “ ‘simply an error in the trial process itself ” and not a “ ‘defect affecting the framework within which the trial proceeds.’ ” Neder, 527 U.S. at 8, 119 S.Ct. 1827 (quoting Arizona v. Fulminante, 499 U.S. 279, 310, 111 S.Ct. 1246, 113 L.Ed.2d 302 (1991)). Because such an error is not “structural,” it “does not necessarily render a criminal trial fundamentally unfair or an unreliable vehicle for determining guilt or innocence.” Id. at 8-9, 119 S.Ct. 1827.
Non-structural constitutional errors like the one at issue here are therefore subject to harmless error review. See Chapman v. California, 386 U.S. 18, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967). When “a reviewing court concludes beyond a reasonable doubt that the omitted element was uncontested and supported by overwhelming evidence, such that the jury verdict would have been the same absent the error, the erroneous instruction is properly found to be harm*939less.” Neder, 527 U.S. at 17, 119 S.Ct. 1827; see also Gracidas-Ulibarry, 231 F.3d at 1197 (error is harmless if “we conclude that it is ‘clear beyond a reasonable doubt-that a rational jury would have found the defendant guilty absent the error’ ” (quoting Neder, 527 U.S. at 18, 119 S.Ct. 1827)). If the error is harmless, we will affirm the conviction regardless of whether the instruction omitted or incorrectly described an element of the offense. See Neder, 527 U.S. at 9-10, 119 S.Ct. 1827; cf. United States v. Larson, 495 F.3d 1094 (9th Cir.2007) (en banc) (affirming despite an acknowledged Confrontation Clause error because the error was harmless), cert. denied, — U.S. -, 128 S.Ct. 1647, 170 L.Ed.2d 359 (2008).
Notwithstanding the defect in the trial court’s instructions — and based on the evidence and argumentation actually presented to the jury — we hold it is clear beyond a reasonable doubt that any rational jury would have found Smith guilty even absent the error.
An object is a dangerous weapon within the meaning of 18 U.S.C. § 113(a)(3) if it is either “inherently dangerous” or otherwise “ ‘used in a manner likely to endanger life or inflict great bodily harm.’ ” United States v. Riggins, 40 F.3d 1055, 1057 (9th Cir.1994) (quoting United States v. Guilbert, 692 F.2d 1340, 1343 (11th Cir.1982) (per curiam)) (finding a “belt” and a “shoe” to be dangerous weapons given “the manner in which the object[s] w[ere] used”). Inherently dangerous weapons, or “ ‘dangerous weapons per se,’” are “‘obviously dangerous’” objects such as “ ‘guns, knives, and the like.’ ” Id. (quoting Guilbert, 692 F.2d at 1343). Although we have not previously defined “great bodily harm,” we find guidance in the definition of “serious bodily injury” in § 113(b)(2) (incorporating by reference the definition of “serious bodily injury” in § 1365(h)). Therefore, we hold that “great bodily harm” is any harm that involves “(A) a substantial risk of death; (B) extreme physical pain; (C) protracted and obvious disfigurement; or (D) protracted loss or impairment of the function of a bodily member, organ, or mental faculty.” See 18 U.S.C. §§ 113(b)(2), 1365(h)(3).
Here, “overwhelming and uncontradict-ed evidence at trial” indicated both that the prison-made knife was inherently dangerous and that it was used in a manner that risked great bodily harm to Jeffries. See United States v. Hollis, 490 F.3d 1149, 1157 (9th Cir.2007) (holding that jury instruction errors are harmless when there is “overwhelming and uncontradicted evidence at trial” concerning the omitted element).
It is undisputed that the knife was formed by melting Styrofoam meal trays into a hard, flat, six-inch-long shank, which was sharpened to a dagger-like point. Nísperos provided uncontradicted expert testimony that the knife did cause “full skin thickness” lacerations about Jeffries’s head and face, and that it could have caused “very fatal injuries.” Smith did not challenge these expert conclusions on cross-examination and, as his counsel conceded at oral argument, entered no evidence at trial to rebut a conclusion that the shank was a dangerous weapon. There is therefore no reasonable doubt that any rational jury would have found that the prison made knife at issue here — designed for, and capable of, inflicting great bodily harm — was an inherently dangerous weapon within the meaning of 18 U.S.C. § 113(a)(3).
It is also clear beyond a reasonable doubt that any rational juror would have found Smith used the prison-made knife in a manner likely to inflict extreme physical pain, cause obvious disfigurement, or impair the function of a bodily organ. While *940Jeffries did not require hospitalization, he sustained “very extensive injuries],”3 including two lacerations penetrating the entire thickness of his skin about his head and face. He also nearly lost an eye: Smith’s counsel conceded at oral argument that the evidence established that the ten centimeters long laceration within the fold of Jeffries’s inner eyelid was caused by the shank and that, if Smith’s stroke had “been more precisely targeted,” Jeffries could have lost the eye and thereby sustained serious bodily injury.4 Given the evidence before the jury regarding the severity and location of Jeffries’ injuries, it is clear beyond a reasonable doubt that any rational juror would have found that Smith’s specific use of the prison-made knife was capable of causing serious bodily injury.
Whether the jury found Smith did not intend to kill Jeffries,5 and whether Smith did in fact inflict great bodily harm within the meaning of the law, are both immaterial to whether Smith used the shank in a manner that made it likely that Jeffries would suffer such harm. As the dissent itself acknowledges, “Smith struck him with a sharpened object in a downward motion with a high degree of force” about his face, head, and shoulders, [Dissent at 3753], causing, in Nisperos’s words, “very extensive injuries].” Those injuries demonstrate that Smith used the shank in a manner that seriously risked blinding Jef-fries in his right eye and otherwise inflicting extreme physical pain. See Riggins, 40 F.3d at 1057 (belt and shoe were dangerous weapons where defendant beat child “as hard as she could” and expert testified victim could have suffered severe injury or death, despite fact that victim “only suffered welts and bruises”). The overwhelming and uncontradicted evidence therefore leaves no doubt that Smith’s use of the weapon was “ ‘likely to ... inflict great bodily harm’ ” upon Jeffries. Id. at 1057 (quoting Guilbert, 692 F.2d at 1343).
Smith nevertheless argues the error in the jury instructions was not harmless *941because the evidence demonstrating the prison-made knife was a dangerous weapon was both “underwhelming” and “contested.” Neither claim is persuasive. Although Smith contested Nisperos’s certification as an expert, he never once challenged any of Nisperos’s unambiguous expert opinions about the nature of the shank or the extent of Jeffries’s injuries.
Smith points to Lieutenant Bengford’s testimony that the unaltered Styrofoam food trays from which the shank was fashioned were “thin, very thin plastic” and “would not be perceived as a possible weapon or a potential weapon” to argue the jury could have found the shank was not a dangerous weapon. But this testimony was unambiguously elicited for the purpose of casting doubt on whether Smith had himself melted the trays to create the shank, not whether the shank was indeed a dangerous weapon. In fact, the exchange between Smith’s counsel and the prison official on this issue concluded as follows:
Q: [W]as [there] evidence consistent with creating a weapon in Mr. Smith’s cell ... ?
A:.... So, no, if a tray was — because they’re thin, very thin plastic, these common-fare trays, where the meat item comes in. It’s only about a three-by-five-inch piece of plastic. So it’s not considered, in itself, as a potential weapon.
Q: But when it’s melted doum or burnt, it is a weapon; correct?
A: When you accumulate a few of those, you could put them together and melt it down into a weapon, yes.
Q: Okay. And in this case, there was no evidence that was consistent or showed that Mr. Smith had created this weapon in his cell; correct?
(Emphasis added.) Thus not only did Smith never submit any evidence or argue before the jury that the prison-made knife was not a dangerous weapon, but his counsel’s questions assumed (if not conceded) that it was a “weapon.” In fact, throughout the entire three-day trial, Smith’s counsel consistently referred to the implement at issue here as a “knife” and a “shank” — words that both colloquially connote inherent dangerousness.6
C.
In the absence of any evidence or argument before the jury to contest the government’s overwhelming case, it is clear beyond a reasonable doubt that any rational juror would have found the prison-made knife was a dangerous weapon within the meaning of 18 U.S.C. § 113(a)(3), regardless of whether the jury instructions were constitutionally defective.
III.
A.
Smith also challenges the terms and conditions of his sentence. “ “We review de novo the district court’s interpretation of the United States Sentencing Guidelines, review for clear error the district court’s factual determinations, and review for abuse of discretion the district court’s applications of the Guidelines to the facts.’ ” United States v. Gomez-Leon, 545 F.3d 777, 782 (9th Cir.2008) (alteration omitted) (quoting United States v. Holt, 510 F.3d 1007, 1010 (9th Cir.2007)). “We must reverse if the district court committed a significant procedural error, such as *942incorrectly calculating the advisory Guidelines’ sentencing range.” Id. at 782-83 (citing Gall v. United States, — U.S. -, 128 S.Ct. 586, 597, 169 L.Ed.2d 445 (2007); United States v. Carty, 520 F.3d 984, 991-93 (9th Cir.) (en banc), cert. denied, — U.S. -, 128 S.Ct. 2491, 171 L.Ed.2d 780 (2008)).
B.
As a condition of his supervised release, Smith was required to submit to an unspecified number of non-treatment drug tests. The district court did not state the maximum number of drug tests Smith was required to take, and the government concedes that this failure constituted an impermissible delegation of the court’s statutory duty under 18 U.S.C. § 3583(d). See United States v. Stephens, 424 F.3d 876, 883-84 (9th Cir.2005).7
Smith argues further that the district court applied the wrong standard to his request for concurrent, rather than consecutive, sentences. The government has also conceded that the district court erroneously consulted U.S.S.G. § 5G1.3(a), rather than U.S.S.G. § 5G1.3(c), when it denied Smith’s request for concurrent sentences. Because “the sentence imposed ... [was] a result of an incorrect application of the Guidelines,” and we cannot say that “the error did not affect the district court’s selection of the sentence imposed,” a “remand is required under § 3742(f)(1).” Williams v. United States, 503 U.S. 193, 202-03, 112 S.Ct. 1112, 117 L.Ed.2d 341 (1992).
Accordingly, we AFFIRM Smith’s conviction, VACATE the sentence imposed, and REMAND for resentencing as to the conditions of his supervised release and the decision to impose Smith’s sentence concurrently, partially concurrently, or consecutively to his undischarged term of imprisonment.
Conviction AFFIRMED; sentence VACATED; REMANDED for resentenc-ing.