The Box Four E-Bike Cassette offers high gears with more teeth to withstand the rigours 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 sprockets are stamped from steel, given our durable black coating and then the larger sprockets are pinned to each other with spacers for easy installation.