XHSPORT 350mm Aluminum Seat Post Mountain Bike Bicycle Seatpost 25.4-31.6mm Material: aluminum alloy. Color: black Matte surface, durable in use. With adjustable head, convenient to install. Aluminum with incremental adjustable clamp Length: 350mm. External diameter: 25.4mm, 27.2mm, 28.6mm, 30.4mm, 30.8mm, 31.6mm