This product is suitable for retrofit folding bike, city bike, electric bike. Supports variable speed freewheel. , high axial strength and compatibility. Standard precision machining, chain retention, increases service life, and reduces friction. A good replacement for bike repair and upgradation, compatible with many bike models. 170mm crank arm length without any overlap of crank arm and chain ring bolt. Colour: silver Material: aluminum alloy Package Contents: 1 * chain ring with crank 1 * crank Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Note: 1. Please allow 1-3 mm error due to manual measurement and 1-3g weight error make sure you don't mind before ordering. 2. Due to the lighting of the photos and the difference of monitors, the pictures may not reflect the actual color of the real item. Please make sure you don't mind before ordering, thank you! About Shipping: 1.please pay attention to your delivery address such as: name, street, house number, doorbell/email without name, etc. is correct, or the order will not be delivered correctly. 2.All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances. 3.During the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours Hope you have a pleasant shopping experience!