The Reptilia 9.40" M-LOK Handguard is a premium free-float rail system engineered for the AR15 platform and compatible with all M4 upper receivers. It features Reptilia's patented turnbuckle technology, which utilizes a reverse-threaded nut assembly to create high-tension pressure against a standard 1.25-inch driven barrel nut, ensuring a rock-solid, anti-rotational lockup. Precision-machined from either 6061-T6 or 7075-T6 billet aluminum depending on the production run, this lightweight handguard offers seven sides of M-LOK mounting slots and a full-length Picatinny top rail, all protected by a rugged MIL-STD Type III hardcoat anodized finish. Reptilia 9.40" M-LOK Black Handguard for M4 Upper Receivers 100-330