SRM Arms Magazine, 12 Gauge, 16 Rounds, Fits SRM M1216, Polymer, Flat Dark Earth SRM1216MSS This is a Rotary" Detachable high capacity magazine that holds 8" 12" or 16 rounds of either 2-3/4 or 3 inch shotshells. It fits the SRM 1216 and provides unsurpassed firepower" force multiplication" and tactical advantages.