The Box Components Three Prime 9 E-Bike cassette features larger initial sprockets to enhance durability against the rigors of modern E-Bike riding. The additional tooth on each of the first three cogs provides longer lifespan and reduced wear, as the force is distributed over a larger area. The Box Components Three Prime 9 E-Bike cassette is designed in line with the cassettes from the Box One and Box Two product lines to achieve an excellent balance of durability, quality, and price. All cogs are made of steel, as is the structure that holds them. The weight is kept low thanks to the numerous holes in the cogs.