Angstadt Arms Ultra Light Handguard, 5.5, M-LOK, Anodized Finish, Black AA055HGMLT Aggressive design" ultra light 5.5" free float hand guard. Their 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.