WantMall Bike Aluminum Handlebarbar Mount Standard 30-31.8mm for Gopro Hd Hero 2 3 Compatible with all GoPro Hero2 and Hero3 cameras and housings CNC machined aluminum, weighs just 43 grams Eliminates vibrations from filming Inner diameter: 30-31.8mm Easy to install to handlebars,seaposts,ski poles etc,great for fast switching between mounts