Features1Made of good quality aluminum alloy material, durable and anti-rust. 2Can protect the crank from scratches, water and dust. 3Double washer, compatible with ordinary hollow sprocket. 4Tighten, seal and waterproof. 5Can be applied for mountain bikes, road bikes, etc.SpecificationFeatures:1. Made of good quality aluminum alloy material, durable and anti-rust.2. Can protect the crank from scratches, water and dust.3. Double washer, compatible with ordinary hollow sprocket.4. Tighten, seal and waterproof.5. Can be applied for mountain bikes, road bikes, etc.Specifications:Material: Aluminum AlloyColor: BlackSuitable Diameter: 22-24mm/0.87-0.94in(Approx.) Package Included:1 * Crank Anti-dust Cover1 * Spare Waterproof RingPackage List