Origin8 GritGuard Seatpost Clamp 31.8 Black AL6061Seatpost clamp with integrated cover prevents dirt and mud from entering the frame at the seatpost junction. Rounded edges and ovalized hole design protects carbon frames and seatposts. AL6061 T6 alloy clamp with NBR cover. 31. 8mm for 27. 2mm seatpost and aluminum frame. 34. 9mm for 30. 9mm seatpost and aluminum frame or 31. 6mm seatpost and carbon frame. 16mm height TECH SPECS Vendor Origin8 Manufacture Number Model Name GritGuard Seatpost Clamp