Bike Suspension Seatpost Shock Mount Tube Double Nail And Track Design For 27.2mm/28.6mm/30.4mm/30.9mm/31.6mm Features: 1. Functional Design: Soft and hard adjustable high-performance shock absorption one-piece molding filtering vibration applicable to the market. Most of the bow saddle on the market no more bump enjoy a comfortable riding experience. 2. Multi-layer High Elasticity Firearm: The spring has high elasticity and enough toughness and plasticity to prevent sudden brittle breakage under the action of impact. 3. Process Design: The reed steel has good hardenability and low susceptibility to overheating and decarburization which can reduce the surface roughness of the spring and improve its service life. 4. Adjustable: Double nail and double track adjustable angle adjust the angle of the cushion according to your own needs thus improving the comfort of riding. 5. Waterproof and Dustproof: Multi-layer sealing ring to prevent rain mud and dust from entering effectively protect the internal cleanliness of the seat tube protect the internal oil does not leak out to maintain lubrication. Specifications: Diameter: 27.2mm/28.6mm/30.4mm/30.9mm/31.6mm Material:Aluminum alloy includes: 1 *Seatpost