1Made of quality metal material, high strength, sturdy and durable. 2Hollow design, lightweight and compact size, easy to install and use. 3With screw and nut, can be fixed firmly, hard to fall off. 43 different color and 2 different size for you to choose, meet your different needs. 5Wonderful accessory for mountain bike, road bike. Item type: Bicycle Seat Clamp Material: TC4, aluminum alloy Optional Color: black, red, blue Optional Size: 31.8mm, 34.9mm 7075AL-T651 Nuts TC4 Titanium alloy gasketT C4 Titanium alloy bolts 7075-T651 aluminum alloy nut, anodized coating, high hardness, the thread is not easy to screw, TC4 titanium alloy screw, high hardness titanium alloy material, guarantee strength. 7075-T651 aluminum, tensile strength: 524Mpa Hardness: 146HB (18.5HW) Yield strength: 455MPa Rod diameter you can infer'the required seat tube clamp specifications:1, Rod diameter: 27.2mm/28.6mm,you choose 31.8mm seatpost clamp(not suitable for fixed gear); 2. Rod diameter: 30.4mm/30.8mm/30.9mm/31.6mm.you choose 34.9mm. border: .5pt solid000;};border: 1px solid000important;}1 x Bicycle seat clamp1 x Screw nut1 x Screw1 x Gasket