This product is suitable for retrofit folding bike, city bike, electric bike. Supports variable speed freewheel.lightweight, 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 .Colour: silverMaterial: aluminum alloyPackage Contents:1 * chain ring with crank1 * crankOnly 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.