Genuine OEM Toyota Radiator Reserve Tank Cap, part number 164050T070. This cap is a critical component of the engine's cooling system, responsible for maintaining the correct pressure within the reserve tank. Proper pressure regulation is essential for preventing coolant boil-over and ensuring efficient heat dissipation. The cap features a precise sealing mechanism to hold pressure and a relief valve for safety. Genuine OEM parts guarantee the exact specifications required for optimal cooling system performance and longevity.