【MATERIAL】Seatpost clamp made of 6061 aluminum alloy,strong and durable. 【SIZE&FIT】Diameter 31.8mm(fit 27.2mm 28.6mm seatpost);Diameter 31.9mm(fit 30.4mm 30.8mm 31.6mm seatpost). 【QUICK RELEASE】Quick release lock design,easy and convenient to install and use,you can adjust the clamp on the way even without any other tools. 【HOLLOW DESIGN&COPPER GASKET】Light weight hollow design;Clamp gasket made of copper,more wear-resistant,make clamp longer life. 【PACKAGE INCLUDED:1 X Bike seatpost clamp, Manufacturer: UPANTECH