Comparison : Item # 21CC4M-H2, 0.106 Inch (in) Orifice Diameter Cone Check Valve
Item # 21CC6M-H2, 0.201 Inch (in) Orifice Diameter Cone Check Valve
Item # 21CC9M-H2, 0.307 Inch (in) Orifice Diameter Cone Check Valve
Item # 21CC12M-H2, 0.438 Inch (in) Orifice Diameter Cone Check Valve
Item # 21CC16M-H2, 0.562 Inch (in) Orifice Diameter Cone Check Valve