Made of aluminum extrusion, this coupler features a removable rubber pad inside which allows to fit for any tube size or Gimbal handlebar comes with dia. 25mm or 30mm. There are also various threaded holes including 3/8”-16 (2 pcs), 1/4”-20 (7 pcs) and M4 (4 pcs) on the main base to accept a wide range of adapters, grip accessories, cameras, lights or monitor arm . etc.