This 3/8" Manfrotto Anti-Rotation Adapter for Friction Arms, with its unique shape, allows the equipment to be securely interlocked so the arm, clamp, or tripod tap in use does not permit rotation. The adapter can easily be mounted or removed using the included hex key. It is compatible with the 244Mini Friction Arm, 244 Micro Friction Arm, 244 Micro Friction Arm with Anti-rotation, the 386B-1 Nano Clamp, and 055 and 190 Series tripods.