Fuji Racing Max Grip Group A Timing Belt Tensioner Cap
The Fuji Racing Max Grip Group A Timing Belt Tensioner cap is an ancient design originally used on WRC / Group A cars before they switched to a dual belt system.
This small cap simply fits over the end of the hydraulic tensioner to allow additional tension in the timing belt system.
Overall, this helps reduce the risk of the timing belt skipping.
The matching Timing Belt Tensioner is this one and Timing Belt Tensioner bracket from Torque Solution