RifleBlok™ 556 universally fits into any rifle chambered in .223 Remington/5.56 NATO. Each RifleBlok™ 5.56 comes with one (1) RifleBlok™, three (3) MagBlok™ 556 magazine inserts*, and an instruction booklet. Your firearm does NOT have to be disassembled to use RifleBlok™. Simply insert RifleBlok™ to train, and remove it to return your firearm to its ready state. RifleBlok™ is SAFE, REALISTIC, TRAINING!