Update your semi with a key element to equalize the speeds of different transmission components, with the Fuller- Transmissions Synchronizer Replacement Kit that ensures you're Ready for the Road Ahead. With a specialized 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. Crafted with top-tier materials to provide long-term reliability and durability. FleetPride is your First Click in Heavy Duty.