Engine Coolant Replacement Radiator Cap (31527) by Gates®. Pressure: 13 psi. Type: Optional System. Shell Diameter: 2.33". Filler Neck Outside Diameter: 2.13". Cap Depth: 1.25". Filler Neck Inside Diameter: 1.61". Filler Neck Depth: 0.75". If you want to keep your vehicle safe on the road for many years to come, go with this Gates product. Developed with the utmost attention to detail and manufactured from the highest quality materials, it is sure to provide a long-lasting service life.