Specter M-4 / CAR-15 Modular Buttstock Magazine Pouch (BMP) holds 1 spare 30 round magazine on the offside of the buttstock. Secure, but readily accessible, this provides the shooter a spare magazine that’s always with the weapon. A highly valuable feature of this BMP is that it’s modular, completely ambidextrous, and may used be with any of our collapsible stock M-4 / CAR-15 CQB, CST, or SOP slings.