The circular end cap for LR-308 free float quad rail handguards installs at the front of free float quad rail or KeyMod handguards without contact to the barrel, for a tighter, cleaner look. 1.98" in outside diameter and 1.30" in inside diameter, it will fit tightly on Monstrum Tactical LR-308 Free Float Quad Rail Handguards, LR-308 Free Float Keymod Handguards, and similarly designed models. It secures quickly and easily via four set screws with the included hex key, no gunsmithing equipment required. It is made from aircraft grade aluminum and weighs only 0.5 ounces. Also Available for AR-15 handguards.