The Sig Sauer M17 ProForce 6mm 21rd BB Magazine with CO2 housing, designated by the part number AMPF-M17, is designed for use with the Sig Sauer M17 ProForce Airsoft Pistol. This Sig Sauer AMPF-M17 magazine accommodates 21 rounds of 6mm BBs and incorporates a CO2 housing to power the airsoft pistol. It's a durable and reliable accessory tailored for realistic training and recreational airsoft shooting, offering extended shooting sessions before needing to replace CO2 cartridges or reload BBs. Sig Sauer M17 ProForce 6mm 21rd BB Magazine w/CO2 Housing AMPF-M17