ATI 5.7x28 50 Round Magazines are designed for FN PS90 and Five Seven AR Uppers. This polymer magazine is a rough, tough customer. The small width and length of a 5.7x28 cartridge allows the magazine to remain small and light. Stop wasting time reloading at the range and in the field. The old west lever action guns were famous for an owner being able to load them on Sunday and then shoot all week. This magazine allows you to load on the 1st and shoot all month! Grab one of these magazines before a dreaded ban could go into effect!