The Mishimoto factory - fit boot kit with DuraCore technology is the perfect upgrade in performance and reliability for your 5.9L Cummins.Mishimoto DuraCore technology is the synthetic material that comprises the innermost layer of all Mishimoto silicone diesel boots.Compared to normal silicone, DuraCore provides superior resistance to heat, pressure, fuel, and oil.This effectively increases the life of our boots by preventing leaks and blowouts.To add even more reliability this kit includes Mishimoto constant - tension T - bolt clamps for accurate and consistent holding power.As with all Mishimoto products, this boot kit is protected by our signature lifetime warranty.