Leosportz Bicycle Bike Quick Release Seatpost Clamp,31.8mm 34.9mmBlack Brake Shoe  (Black, Black)

Your choice of seat clamp size depends on the frame tube size where the seatpost enters the frame (seat tube). We would recommend that you remove your old seat post clamp and measure the frames external seat tube diameter to give the size required. It should match up to the sizes listed in the options