ORDER

Wisconsin inmate Quincy Benjamin, early into his 51-year sentence for rape, sent a letter through the United States Postal Service to a witness in the rape case, threatening to kill the witness or his family unless money was sent to him in prison. This was his second such incident: only a month before, he had been sentenced to 35 months — with 11 of those months to run consecutive to his state sentence — for mailing threats to the state prosecutor who prosecuted him in the earlier proceeding. Benjamin pleaded guilty to knowingly using the U.S. Postal Service to make threats, see 18 U.S.C. § 876(c), and was sentenced to 24 months’ additional imprisonment. Benjamin filed a notice of appeal, but his appointed counsel has concluded that the appeal is frivolous and seeks to withdraw. See Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967). Benjamin has not responded to his counsel’s submission. See Cir. R. 51(b). We limit our review to the potential issues identified in counsel’s facially adequate submission. See United States v. Schuh, 289 F.3d 968, 973-74 (7th Cir. 2002).

Benjamin has informed his lawyer that he wants to challenge only his sentence on appeal, so counsel’s brief properly omits any discussion about the plea colloquy or the voluntariness of the plea. See United States v. Konczak, 683 F.3d 348, 349 (7th Cir. 2012); United States v. Knox, 287 F.3d 667, 671 (7th Cir. 2002).

*605Counsel considers whether Benjamin could challenge the reasonableness of his 24-month prison sentence but appropriately rejects such a challenge as frivolous. The prison term is at the bottom of a properly calculated guidelines range (24-30 months) and thus is presumptively reasonable. See Rita v. United States, 551 U.S. 338, 347, 127 S.Ct. 2456, 168 L.Ed.2d 203 (2007); United States v. Pillado, 656 F.3d 754, 772 (7th Cir. 2011). Counsel identifies no sound reason to disturb that presumption. The district court assessed the factors in 18 U.S.C. § 3553(a), and reasonably concluded that a within-range term is necessary to provide adequate deterrence, and reflect both Benjamin’s criminal history and the seriousness of the offense.

The motion to withdraw is GRANTED, and the appeal is DISMISSED.