Bike Seat Post Size The bicycle seatpost is 300mm long, 3mm thick and 27.2mm (1.07") in diameter, and fits most road bikes. (Note: Please measure and confirm wher the outer diameter and length of your bicycle seatpost matches this item before purchasing, our picture has a measurement method. ) High Strength Material The seatpost is made of iron, which is high strength, strong and durable. With black coating, exquisite workmanship, nice touch feeling, good corrosion resistance. Ideal replacement for worn or broken seat post of most mountain bike. Easy to Install Just loosen the saddle clamp of your old seat and remove your seatpost, then fix the saddle clamp to the new seatpost and install it into your bicycle frame, then will be finished. Please note that the saddle clamp is NOT included. Safe Line Mark There is a safe line markings on the bottom of the seatpost, please insert at least above the minimum safety line to prevent hidden dangers. As well as seatpost shafts are sanded to ensure smooth ends to prevent you from getting scratched. Suitable for Bike Seat with Saddle Clamp Thickened bicycle seat tube is more firm and safer. This Bike Seat Post suitable for most road bike, mountain bikes, downhill bike, track bike, fixed gear bicycle, foldable bicycle and so on.