ductile iron flexible coupling 
Size and working pressure
DN20 to DN125 350psi (25bar)
DN150-DN300  300psi  (21bar)
Housing : ductile iron to ASTM A536
Surface treatment:
Antirust paint red or blue
Hot-dipped zinc galvanized
epoxy power
rubber gasket: gasket seals is C-shaped ,made of  standard gasket EPDM
for cold water,hot water ,rare acid,oil-free air and mulitple chemical product(-50-150°C)It is not suitable for medium like petroleum
bolt&nuts: round-head, elliptoid-neck ,carriage bolt ,type carbon iron covered with zinc or decromet