MCTi Black Alumium 30.8x450mm MTB Road Cycling Bicycle Bike Seatpost Seat Post Material: Aluminum 6061,Light weight,never rust. Strength: 4.9 levels ultra high strength, maxium of 580lbs ; Setback: 20mm. Adjust tube length of 0 to 320mm. Size: 27.2x450mm(apx 350g/pc),28.6x450mm(apx 360g/pc),30.4x450mm(apx 390g/pc),30.8x450mm(apx 410g/pc),31.6x450mm(apx 420g/pc) Total length: 450mm, Tube Length: 425mm, Head Length: 25mm Type: Black Setback seatpost. Good for Road, Mountain Bike Seatpost.