QUALITY:Made of premium , lightweight, high strength and deformation resistance, durable for long time use. CRANK ARE LENGTH: 170mm crank arm length without any overlap of crank arm and chain ring bolt. PERFECT CUTTING: Standard quality cutting of hole, which ensures to bike, easy to install. Suitable for road bike, mountain bike, folding bike, fixed gear bicycle, etc. Note: 10 grooves need to correspond to the bicycle bottom bracket should have 10 grooves. Colour:black :Aluminum Package Contents: 1 x bicycle crank arm Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.