42T Chainring: Steel material, high strength and durable. Aluminiun Alloy Chain Covers and Cranks: Sufficient strength and lightweight to reduce the weight of the entire bicycle. The weight of the Crankset and arm is 0.95kg/2.09LB Suit for: E bike City bike and folding bicycle Compatibale with: Single speed bicycle and electric bike, 6/7/8/9 gear bicycles and electric bike Double Wall Chain Cover: Prevent the chain from slipping, protect the chain, and make it more aesthetically pleasing WEEROCK E Bike/ Bike Crankset 1 Piece/Single 42T Chainring Crankset with Aluminium Alloy Double Chain Cover 170mm Arm 104mm BCD for Single Speed and 6/7/8 Speeds Electric Bike,Bicycles, Folding Bicycle