This Nato rail clamp with a ball head can replace the 1/4"" or 3/8"" versions and add extra security and speed with its sliding function. It can also prevent twisting and loosening.You can slide this onto any standard Nato rails and tighten it via its thumbscrew.This Nato rail clamp with ball head is compatible with most Magic Arms, Friction Arms, and Israeli Arms that use a dual ball head system.One end secures into the magic arm and the other end features a Nato rail clamp receiver. The ball end features a blue rubber gasket for additional grip..