Chain ring: high strength aviation aluminum alloyCrank: high strength aluminum alloy Chain Cover/Decorative Spider: Crafted from engineering-grade plastic, ensuring added protection and a sleek finish. The chainring and chaincover are secured to the crank arm's pawl with screws and nuts, allowing for disassembly chainring is made using a combination of stamping, heat treatment, and CNC machining. The surface is treated with a sandblasted anodized finish for enhanced durability, Crank Arm: The crank arms are produced through precision forging, heat treatment, and CNC machining. They feature a sandblasted anodized finish, ensuring both strength and resistance to wear. Plastic Cover: The protective cover and decorative claw are made from engineered plastic, produced through thermal extrusion and injection molding. This process ensures a strong and durable design while providing a sleek finish. Detachable chainwheel, accurate and fast speed change, fixed gear positioning, no noise, prevent chain drop and trouser entanglement.