Aggressive design ultra light 5.5 free float hand guard. Its unique design features a very slim profile (1.375 ID) that still allows for the installation of a sound suppressor of 1.40 in diameter and smaller to tuck inside of the handguard when used with an exact length 6 barrel. Works with 223/5.56 and 9mm calibers. Handguard does not require timing and installs with a standard wrench. (Will not fit 308 models)