Prestone Super Radiator Sealer"s special formula helps seal larger size leaks. Super Radiator Sealer takes sealing performance to a higher level. Its unique combination of natural and synthetic components provides the ability to seal leaks up to 0.016 inch x 0.5 inch. What makes this possible is the size, strength, and durability afforded by fibrillated Kevlar particles, the same materials in bullet proof vests. Super Sealer"s particles have been chosen to seal even large leaks without interfering with the flow through the radiator and heater core tubes.