DIRECT IMPINGEMENT BUILDERS KIT for the AR-15 Superlative Arms has put together a kit to make it easier for the end-user to get everything they need for the operating system of their AR-15. In this kit you will get a Superlative Arms adjustable gas block with their Patented Bleed OffA(R) Mode and Patented Exterior Locking Detent for the adjustment screw, completed with a pre-installed 304 Stainless Steel gas tube in Melonite (for greater heat and corrosion resistance), and the new Superlative Arms direct impingement DLC (Diamond-like Coating) bolt carrier (bolt, cam pin, firing pin, and firing pin retainer NOT INCLUDED). The Superlative Arms bolt carrier is compatible with all AR-15 Mfg: Superlative Arms Llc