Our M-16 / AR-15 Modular Buttstock Magazine Pouch (BMP) kit holds 1 spare 30 round magazine on the offside of the buttstock. Secure, but readily accessible, this gives the shooter a spare magazine that"s always with the weapon. A highly valuable feature of this BMP is that it is modular, completely ambidextrous and can be easily attached to the rear adapter of any of our fixed stock M-16 / AR-15 tactical slings. NOTE: This BMP Kit is intended to be used in conjunction with your existing Specter Gear sling"s wrap around rear adapter (As shown above) and comes with a magazine pouch and front strap assembly only for attachment to your Specter Gear 2 or 3 point sling"s rear adapter. We do offer a stand alone version that comes with a rear adapter should you not already have a Specter Gear sling attached to your rifle.