Motorcycle 1 inch ball Mount with 9mm Hole and Double Socket Standard Arm for GoPro Hero Camera. (sku 30623)Motorcycle 1 inch ball Mount with 9mm Hole and Double Socket Standard Arm for GoPro Hero Camera. This mount features a base with a 9mm hole and 1 inch diameter rubber ball , a double socket standard arm and a custom GoPro Hero adapter. The base is often used on motorcycles, attaching to the mirror frame. The camera adapter consists of a 1 inch diameter rubber ball connected to a custom GoPro adapter which attaches directly to the under side of the