The BT80 M-LOK Flush Cup Rail is designed for use with all M-LOK compatible hand guards, forends and buttstocks. It has 5 usable slots and a flush cup allowing the use of Flush Cup sling swivels (not provided). The BT80 can be used for the attaching of any of our 1913 Picatinny rail mounted Atlas Bipods, Accu-Shot Monopods or Folding Foregrip. It requires standard M-LOK sized slots for mounting. Machined from 6061-T6 aluminum and Type III hard coat anodized. It comes with two 10-24 x 3/8 fasteners and two M-LOK nuts. Available in black only. Specifications: Length: 2.875"Center-to-center: 1.575"Width: 0.835"Weight: 1.038 oz B& T Industries Atlas M-LOK Flush Cup 5-Slot Picatinny Rail BT80