The Super Modular Rail 13.5" (SMR) MK16 M-LOK®, NSN# 1005-01-672-4794 (13.5”), has been adopted by USASOC for the URG-I program (Upper Receiver Group Improved). The Geissele Super Modular Rail MK16 offers unmatched performance for the most demanding shooters. Mounted to your AR-15 upper using the updated version of the proven Geissele Barrel Nut design, the MK16 is not only easy to install and maintain but offers superior rigidity. Anti-rotation tabs and set-screws ensure that your rail will won’t rotate, even under the most extreme conditions of use. M1913 picatinny rail on top and M-LOK™ slots on every quadrant ensures maximum customization for all your accessories. The Geissele SMR MK16 is precision machined using 6061-T6 Aluminum due to its strong, rigid, and light properties, and is finished in durable Type-3 Hardcoat anodized. A 9.3" variant of the MK16 is also available for users requiring a shorter platform. HEIGHT: 2.39" COLOR:  Black or DDC MATERIAL:  6061-T6 FINISH:  Type 3 Hardcoast Anodize AVAILABLE LENGTHS:  9.3" or 13.5" INNER DIAMETER:  1.26" OUTER DIAMETER (DAQ*):  1.59" SMR MK16 9.3" WEIGHT:  10.1oz (11.74oz w/ barrel nut) SMR MK16 13.5" WEIGHT:  13.4oz (14.9oz w/ barrel nut)