[materials]this crank arm is made of materials, which is sturdy and durable. High strength, high hardness, not easy to deform. Comply with strict quality control standards, reliable in use [materials]this crank arm is made of materials, which is sturdy and durable. High strength, high hardness, not easy to deform. Comply with strict quality control standards, reliable in use [Fine workmanship]sample design, fine workmanship, used for the installation of bicycle mid-drive motors. Size: about 21*3.8cm/6.3*5.9inch; weight: about. 450g [Easy to install]our crank arms are light in weight, small in size, and easy to install and use. Our products have been tested to ensure trouble-free installation and performance, please rest assured to buy [Applicable]our crank arm is suitable for BMX Bike, BMX Bike-Old School, Cruiser, Cyclocross Bike, Electric Bike, Folding Bike, Hybrid/Comfort Bike, Mountain Bike Specification: Item Type: Crank Arms Material: Blend Material Color: Black Size: Approx. 21 X 3.8cm / 6.3 X 5.9inch Weight: Approx. 450g Package List: 2 X Crank Arms