The Oakton Deluxe 1/4 DIN pH/ORP Proportional On/Off Controller allows you to customize this advanced controller to fit your exact application! Select from three control types: on/off, proportional pulse length, or proportional pulse frequency. Use on/off control to shut your pump or valve on or off when your process passes its set points. Use proportional control to gradually increase or decrease your pump’s or valve’s response, depending on the amount by which your process has passed the set point. This controller is also selectable for pH or ORP control; normally activated or unactivated relays; manual or automatic temperature compensation, and much more! The controller’s convenient 1 ⁄4 DIN size fits into standard panel cutouts; it includes mounting hardware for fast panel installation. The IP54 rated front panel keypad is weather resistant.