Cross Machine Tool UHPR MOD1 line of handguards are made from 6000 series extruded aluminum and finished with a Milspec Type 3 Class 2 Hard Black anodize. A proprietary 7075 anodized aluminum barrel nut requires no shims for installation. M-LOK mounting slots are placed at the 3, 6, & 9 o'clock positions, and 4 anti-rotation QD sockets provided sling placement on either side, forward or rear, of the handguard. The handguard is compatible with most known low profile gas blocks. Includes barrel nut wrench. Mfg: Cross Machine Tool Co.