This performance cap has 3 features we favor over here at Fab9, we run these on our own vehicles. First: the LEVAR - every vehicle should come with this feature. It allows you to safely release the pressure from the system before removal. Secondly: silicone mating surfaces to make sure it stays sealed. Finally the increased PRESSURE - what does that mean for your cooling system? The higher the pressure, the higher the boiling point of your coolant will be - keep your fluids from boiling over with this 16psi cap.