The Stern Defense AR-15 SD 15 MOD5 Upper Receiver Assembly features a mil-Spec flat top upper receiver with Stern Defense laser engraved dust cover and forward assist. Machined from 7075-T6 aluminum and hard-coat anodized. Mil-spec dry film lube in the bore. The free float M-LOKhandguard from Stern Defense offers excellent ergonomics while remaining lightweight and strong. This handguard is M-LOKcompatible to accept your favorite attachments. Features a secure clamp on mounting system that ensures that the handguard remains in place even under heavy abuse, sustained full auto fire, and shooting prone from a bi-pod. Machined from 6061 aircraft grade aluminum and hard-coat anodized for longevity and durability. These handguards also feature quick disconnect swivel holes. The SD Comp Brake is manufactured to the highest quality standards. Full auto tested to ensure that the compensator ports keep muzzle rise to a minimum. The twin chamber ports guarantee that every last bit of usable g...