RAM Custom GoPro Hero Adapter with Double Socket Arm and U-Bolt Handlebar Rail Mount (sku 18470)RAM Custom GoPro Hero Adapter with Double Socket Arm and Zinc Coated U Bolt Handlebar Mount. RAM B 149Z GOP1U The GoPro Hero Adapter attaches directly to the underside of the camera, replacing the factory mounting bracket. Zinc coated U Bolt base fits rails from 12. 7mm to 31. 7mm in diameter. Adjustment points at both ends of the 3 inch double socket arm. The rubber ball and socket system absorbs vibration. Mount allows for optimum viewing position.