The PRO Bike Gear Cassette Wrench is a durable, hardened steel tool designed to remove and install bicycle cassettes with 10T and 11T smallest sprockets. It serves as a secure, user-friendly alternative to a traditional chain whip, featuring a long handle for high leverage and an ergonomic grip for comfort. One side is for 10T and you simply flip it over if your smallest cassette cog is 11T.