Sig Sauer 556 this gun is rare and is a collector's item, you don't have to be like everyone else at field and rock a M4 but, if need mag you can get one from a team mate because the sig 556 uses "556" mags or better known as m4/m16 stanag type mags the gun comes with two proprietary mags that connect to one another this is an excellent gun at a low price I almost forgot to mention the upper and lower receiver are metal price includes shipping