The Box Four E-Bike Cassette offers high gears with more teeth to withstand the rigors of modern E-Bike riding. Adding an extra tooth to each of the three highest gears provides increased durability and decreased wear by distributing the load over a larger area! Box Four adapts our Prime 9 philosophy of durability, simplicity, and reliability at a great price point. All cogs are stamped from steel, given our durable black coating and then the larger cogs are pinned to each other with spacers for easy installation. SUPPORT MATERIALS Prime 9 Technology™ View Prime 9 Drivetrain Compatibility Manual How is the Ebike variant different? View Prime 9 E-Bike Comparison Chart Why Prime 9? Please see page 6 of our guide for notes regarding the 2 HG drivers.