BCD: 104mm Note: This product is suitable for BCD104 chainring, 30-speed bicycles. 20 speed bikes cannot use this item Size: suitable for 32T-36T Colour: Black Material: aluminum alloy Package Contents: 1 x Chainlink Bumper Guard Only the above package content, other products are not included. Note: Light reflection 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.