BT8-5420 is a 3/4 in. blue EPDM heater hose for compatible engine coolant and heater circuit applications. It has a 3/4 in. inside diameter and an estimated 1.05 in. outside diameter. This hose is intended for water and glycol-based coolant systems. Cross references may include Gates 28402, Goodyear Hi-Miler 3/4, Applied Industrial 580001191002, Continental 65009, Continental 65010, and OESL Auto 20027891, but color and hose markings should be confirmed before treating those as exact replacements.