If you have the officially licensed Smith & Wesson M&P9 M2.0 .177 caliber bb pistol, this is the spare magazine you need to keep right on shooting. This drop-free magazine holds a single 12-gram non-threaded CO2 cartridge along with 18 BBs. Loading BBs into the loading port is made much easier by the addition of a follower hold-down tab cut into the BB channel. Pick up a spare magazine or two to aid in magazine change drills or just to keep the fun at the range going for a longer time.