Mirror or Pinchbolt Mount with Double Socket Swivel Arm for GoPro Hero Camera. (sku 30619)Mirror or Pinchbolt Mount with Double Socket Swivel Arm for GoPro Hero Camera. This mount features a mirror or pinchbolt base with 1 inch rubber ball, a double socket swivel arm and a custom GoPro Hero adapter. The mirror or pinchbolt mount consists of a 1 inch diameter ball and 57mm x 22mm base with 11mm hole, often used on motorcycles, attaching to the mirror frame. This part fits well on many handlebar pinchbolts with a washer (base is 5mm thick).