Description : Design : Dual screw knob clamps , can be installed upper and lower sides of the clamp base . Material : Made of high quality aluminium alloy , anodic surface , corrosion resistance and wear resistance , durable . Size : 50mm ( 1 . 97 ;) in length , so the adapter jaws can accept from 38 - 42mm wide . Hex Wrench : Comes with a wrench to adjust the direction of the clamp seat , right rotated 90 degree . Anti - skid : Designed with function to your cameras from falling off . Specification : Model : QR - 50B Material : Aluminum Alloy Technology : Anodic oxidation Camera screw : UNC1 / 4 screw Use for : Camera tripod Type : Double layer , double - sided knob screw clamp Size Chart : 90x50mm / 3 . 54x1 . 97inch Package Includes : 1 Piece Clamp 1 Piece Hex Wrench Note : 1 . Please allow slightly error due to manual measurement . 2 . Due to between different monitors , the picture may not reflect the actual the item . 3 shopping !