The M-LOK system offers a new mounting platform for accessories and is lightweight without sacrificing strength or structural integrity. Engineered with advanced ergonomics for comfort and improved performance. Continuous/uninterrupted Picatinny Rail across the top. Accessory rails can be placed at 3, 6, and 9 o'clock positions. QD sling mount positions at 3 and 9 o'clock. Made to fit Magpul QD. Engineered to allow for low profile gas block to fit inside. Specifications and Features:
Length: 4"
Diameter (interior): 1.6"
Width (Exterior): 1.8"
Height (Exterior): 2.1"
Total Weight: 6.35 oz
Material: 6005-T651 Aluminium
Compatibility: Magpul QD
Includes: M-LOK accessory rail (with M-LOK nuts), forend adapter, barrel nut, Vibra-Tite, and six 6-32 screws.

Includes:
One 5-slot M-LOK accessory rail with M-LOK nuts, forend adapter, barrel nut, Vibra-Tite, screws

Fits:

AR-15 upper receivers