Atlas Bipods Barrett M107A1 Rail Black. The center-to-center hole spacing of 3.359in fits the outer two holes of the existing three holes in the chassis. We strongly suggest that you measure the hole spacing on your rifle. The center section is machined to Picatinny rail standards from 4140 cold finished steel with a maganese phosphate finish. Two 3/8-16 x 3/4in flat head cap screws are provided. The original 11/16in nuts and tooth lock washers are reused to complete assembly. Specifications for Atlas Bipods BT79 Barrett M107A1 Rail: Manufacturer: Atlas Bipods Color: Black Length: 2.05 in Weight: 0.576 oz Finish: Maganese Phosphate Fabric/Material: 4140 Cold Finished Steel Country of Origin: USA Features of Atlas Bipods Bipods BT79 Barrett M107A1 Rail An 11/16in socket and ratchet wrench OR break-over bar and a 7/32in hex wrench is required for installation (none included) No modification needed Package Contents: Atlas Bipods Bipods BT79 Barrett M107A1 Rail Atlas Bipods BT79: Bipods BT79 Barrett M107A1 Rail Black