Equip your semi to be Ready for the Road Ahead™, with the Fuller- Transmissions Synchronizer Replacement Kit, a crucial element that equalizes the speeds of different components within the transmission. Thanks to its cone-shaped design, this replacement part is able to make direct contact with the desired gear, and match the speeds of the gear to the gear shaft. Manufactured with durable materials to provide long-lasting reliability. FleetPride is your First Click in Heavy Duty®.