UD ARCA DYNALOCK RAIL The UD Arca Dynalock Rail can be installed using the M-LOK fasteners provided or by a qualified gunsmith. By upgrading to the Arca Dynalock Rail, you can enjoy the benefits of both Arca and Dynalock accessories on your firearm. The most popular enhancement is the ability to use the Orbit Ballhead with Dynalock, all other Arca Clamp accessories are also compatible. SPECIFICATIONS: Materials: 6061 T6 Aluminum Finish: Hardcoat Anodize Weight: 3.00a ^2 - 2.1 oz 6.15a ^2 - 4.2 oz 9.30a ^2 - 6.3 oz 12.45a ^2 - 8.4 oz Width: 1.50" Height: .315" Mfg: Ultradyne Usa