Prepare your semi to be Ready for the Road Ahead , with the Tru-Flex 4" x 36' Medium Duty 409 Stainless Steel Flex Hose that provides a secure transfer of essential fluids throughout the cooling system. This replacement hose works to transfer coolant from the radiator to the engine to reduce heat and optimize motor performance. Engineered with incredible durability and improved bending strength to deliver a long service life, this flex hose also can be used on other systems including exhaust, air intake, and hydraulic systems. FleetPride is your First Click in Heavy Duty .