Crank description: Brand: JIANKUN (IXF) Color: black, red, blue, silver, green,purple,gold Crank Arm length: 170mm Material: AL6061 aluminum alloy Compatible: Single/Double/Triple chainring; for 7/8/9/10/11/12S chainring Bolt Center Diameter: 104mm BCD Weight: about 637g (right & left) Advantages: light weight,stylish appearance,very cool,high strength axle,strong compatibility Chainring description: Brand: SNAIL Color: black, red, blue, green,purple,gold Material: 7075-T6 Aluminum alloy Size: 30-42t Compatibility: 8,9,10,11 speed chain Bolt Center Diameter: 104mm BCD Thickness: 4mm Shape: Round/Oval Fit for MTB Bike,XC/Off Road/AM bike modified single chainring,Fit SRAM/FSA/Prowheel 104bcd crank.Please make sure your crank BCD specification is 104mm BCD before purchasing.