CNC aluminum alloy crank/chainring screws — machined replacement bolts that add strength and style while keeping weight minimal. Key benefits Stronger than plastic: Machined from CNC aluminum alloy for greater durability and reliable fastening compared with stock plastic screws. Lightweight: Each screw weighs only 7 g, so you reinforce your crankset without noticeable added weight. Customizable appearance: Available in black, red, blue and additional color options to match or accent your bike. Precise fit and finish: CNC machining ensures consistent threads and a secure, repeatable fit. What they do and why you need them Secure hollow chainrings and crank covers with metal hardware that resists wear and deformation better than plastic alternatives. Prevent loosening and damage to integrated crank assemblies by replacing aging or stripped factory screws. Offer a quick visual upgrade while maintaining function and low weight. Compatibility and sizes Threaded screws: Compatible with hollow chainrings of FS.A cranksets and older FC 4500 and FC 5600 highway cranksets. M19 threaded screws: Designed for IXF, LEBYCLE and other brands that use M19 fasteners on hollow integrated cranksets. M20 crank-cover screw: Intended for specific kits such as M4000, M590, M596, M661 and other integrated chainring systems that require M20 cover screws. Performance and installation notes Machined threads provide a precise mating surface for proper torque and consistent clamping force. Minimal mass (7 g each) keeps rotating weight low, important for road and performance applications. Use the appropriate thread size (threaded/M19/M20) to match your crankset model; confirm fit before final installation. Typical use scenarios 1) Road bike maintenance: Replace cracked or stretched plastic chainring screws on an older FC 4500 or FC 5600 crankset to restore secure chainring mounting and extend service life. 2) Performance upgrade: Swap plastic fasteners for CNC aluminum M19 screws on an IXF or LEBYCLE hollow integrated crankset to improve durability and maintain a lightweight build for training or racing. 3) Assembly and repair of integrated kits: Install M20 crank-cover screws when building or repairing cranksets that specify M4000, M590, M596 or M661-compatible components. What’s included and sizing reminder Sold as individual screws; each screw weighs approximately 7 g. Confirm your crankset’s required thread type (threaded, M19, or M20) and model compatibility (FS.A, FC 4500, FC 5600, IXF, LEBYCLE, M4000/M590/M596/M661, etc.) before purchase to ensure correct fit.