The Samson M-LOK SX Series features a free-floating rail system and the sleek profile creates a comfortable feel to a wide range of shooters, regardless of your application. The SX system creates a solid extension of the upper receiver with the benefits of rapid and easy installation thanks to the pre-installed, captured clamping system and Samson barrel nut. Included is a QD swivel, hex wrench, and barrel nut wrench.