Features： 1、104mm BCD. 2、170mm length for crank arm. 3、Square tapered crank arms. 4、Compatible with 8 / 9 / 10 / 11 speed. 5、Aluminum alloy material for light weight and strong strength. 6、Suitable for most mountain bikes. 7、Come with a 4-bolt chainring.Narrow\u0026wide teeth increase chain retention and wear life,reduce friction and noise. Specification： Good replacement for your mountain bikes. Features： 104mm BCD. 170mm length for crank arm. Squre tapered crank arms. Compatible with 8 / 9 / 10 / 11 speed. Aluminum alloy material for light weight and strong strength. Suitable for most mountain bikes. Come with a 4-bolt chainring.Narrow&wide teeth increase chain retention and wear life,reduce friction and noise. Specification: Model: 2pcs Crank Arms  /  2pcs Crank Arms& 1pc Chainring (optional) Color: Black / Red (optional) Chainring Teeth: 34T / 36T (optional) Crank Arm: Material: Aluminum alloy Compatible: 8/9/10/11 speed Fits pedal size: 9/16" BCD: 104mm Length: 170mm Weight: approx. 510 g / 18.0 oz (for a pair) Chainring: Chainring Teeth: 34T / 36T (optional) Diameter: 144mm / 153mm Material: Aluminum alloy BCD: 104mm Fits chain size: Standard 1/2" X 1/8" Package List: 1* Right Crank 1* Left Crank Arm 4* Pair of Bolt 1* Chainring Package List： 1* Right Crank 1* Left Crank Arm 4* Pair of Bolt 1* Chainring