The CAC-4221-3 On/ Off Pressure Switch with built in pressure relief unloader is a Furnas 69JF109403R Series Pressure Switch with a cut in preset pressure of 110 psi and a preset cut out pressure of 125 psi. . .This CAC-4221-3 Pressure switch comes standard with the improved unloader valve design as well as a standard plastic lever for manually turning the switch on and off. . . . The CAC-4221-3 Pressure Switch can be used to replace the following part numbers:. . CAC-4221-1 . . CAC-4221-2 . . .CAC-4221-3. . .Z-CAC-4221-1. . .Z-CAC-4221-2. . .CAC-478. . .CAC-478-1. . .Z-CAC-478-1