MINIATURE MASTERKEY SHOTGUN MODEL UNDER AR BARREL ATTACHMENT | REQUIRES SMALL INSTALLATION Fits miniature M16 and AR15 Model Barrels Comes with screw and screw driver. Must remove front sling loop and hand-guards to fit. 5.25" in length (13.3cm) 1.5" in height (3.8cm) Preloaded with 3 dummy shotgun shells Does not fit the short barrel system Not compatible with AR Drum Mag 100% die cast metal Installation Instructions: Remove front sling loop with included screwdriver. Remove hand-guards. Remove bracket from Masterkey. Fit Masterkey under barrel. Front sling loop mount inserts into groove in Masterkey. Position bracket over barrel and onto Masterkey and screw into place with long screw. (Smaller bracket for GoatGun M16 attachment.) Fix larger hand guard into place. When loading rounds, push dummy shells all the way in using small screw driver provided, or a toothpick or related item. When cycling, pull firmly to eject round. Compatible with M16A1 when using the Grenedier handguard. Is your MasterKey jammed? Use this video below: