Made of High quality 6061 aluminium alloyLight weightnever rustStrength 49 levels ultra high strength maxium of 580lbs Only fit for Seat Post Diameter308mm or 309mmLength350mmSetback 20mm Adjust tube length of 0 to 320mmTo choose the correct seatpost size please measure inside diameter of the frame before you buy it How to Choose the Size1Check the diameter of the original seatpostchoose the same size as the original diameter2Measure the inside diameter of the frame tube With adjustable head convenient to install Suitable for most mountain bikes road bike fixed gear bicycle downhill bike track bike MTB BMX DH etc