Vktech&reg; GUB G-23 Anodised Alloy Bike Water Bottle Holder Seat Post Bar Rack Mount CNC 7075 Alloy Anodised Seat Post or Bar Mount Cage Bracket Mounts to 30.9mm or 31.6mm Seat Post or 31.8mm Handlebars via Hinged Mounting Bracket Bracket turns 90 degrees to suit mounting position Complete with bolts Weight: 42 Grams