The Model C307 Transition Coupling provides for a direct connection between grooved end IPS steel pipe, fittings or valves and grooved end CTS copper tubing. The C307 is comprised of two ductile iron housings, pressure responsive rubber gasket and track bolts and nuts. The rubber gasket isolates the fluid from coupling housings and the epoxy coated housings help eliminate galvanic local cell and stray current problems.