; (C) no restricted diet or any other change in diet shall be imposed as a form of punishment; and (D) an inmate shall— (i) always have access to any authorized personal property belonging to the inmate; and (ii) regardless of the unit the inmate is housed in or the status the inmate has been assigned, always have access to the commissary and to contact visitation with visitors, except where there is a specific significant risk to the physical safety of the inmate, other inmates, staff, or the public. (6) Special housing units The Director of the Bureau of Prisons, the Director of the United States Marshals Service, and any facility that contracts with the Bureau of Prisons or the United States Marshals Service shall— (A) limit administrative segregation— (i) to situations in which such segregation is necessary to— (I) control a substantial and immediate threat that cannot be addressed through alternative housing; or (II) temporarily house an inmate pending transfer, pending classification, or pending resolution of another temporary administrative matter; and (ii) to a duration of not more than 15 consecutive days, and not more than 20 days in a 60-day period, unless— (I) the inmate requests to remain in administrative segregation under paragraph (3)(D)(i); or (II) in order to address the continued existence of a substantial and immediate threat, a multidisciplinary staff committee approves a temporary extension, which— (aa) may not be longer than 15 days; and (bb) shall be reviewed by the multidisciplinary staff committee every 3 days during the period of the extension, in order to confirm the continued existence of the substantial and immediate threat