30.8mm Aluminum Seat Post Mountain Road Bike MTB Bicycle 350mm Black Brand new MTB BMX road bike bicycle seatposts.One piece forged alloy. Two-bolt design for easy to adjust, vise-like grip. Low profile clamp won't bottom out on saddle. Wide saddle clamp reduces stress on lightweight saddle rails. Superior fatigue and impact strengt. Material:Alloy. Size: 30.8mm/ 1.2inches. Overall length:350mm/ 13.7inches.