The engine coolant heat causes coolant hose pressure and temperature to increase and expands the OEM rubber hose reducing coolant water pressure. Age and heat also causes deterioration of the OEM rubber hose. The j's racing coolant hoses are produced by SFS and have a greater resistance to expansion under extreme temperatures and pressures. The polystar 3-laye silicone construction has excellent heat and pressure resistance. The silicone material is also much more durable over the OEM rubber hose for longer lasting operation. Colour is red to increase engine appearance