M:part QR Seat Clamp You can tell the M:part QR Seat Clamp is very well made from its quick release lever's smooth, positive action. The M:part QR Seat Clamp's mostly black anodised heat treated 6061 aluminium construction makes it strong and light weight. The QR lever's through-bolt is steel for extra strength where required. Available in the three most common seat tube sizes: 28.6, 31.8 or 34.9mm outside diameter. A lip at the top of the clamp seats it securely in place. The M:part QR Seat Clamp can be fitted to most bikes. This QR makes it easy to adjust bicycle saddle height so it's especially useful for bikes that get shared out. Weight: 57g - based upon weighing one M:part QR Seat Clamp 31.8mm at Bike Co-op HQ in April 2015. Be aware that cycling equipment specifications can change without notice so please regard our published weights as an honest but approximate guide.