These auto flush valves come with, or without a flow restrictor.  They automatically flush the RO membrane each time the system is energized, and once per hour during use. Make your selection (above) based on the GPD capacity of the RO membrane, or if you are using a separate flow restrictor, choose the auto flush valve without a flow restrictor.  

Valves with flow restrictors are designed to be matched to the gallons-per-day capacity of your RO membrane, assuming the RO or RODI system feedwater is at 60 PSI and 77 degrees F.  If you have lower pressure, and/or lower water temperature, consider selecting an auto flush flow restrictor for a lower capacity membrane.

These devices have a single Aquatec-compatible plug. These units include a wiring harness splitter (Buckeye Hydro Part No. 0502), and plug into the same wiring as an Aquatec booster pump / transformer assembly - or they can be run independently (without a booster pump) with the same transformer. If run without a booster pump, Buckeye Transformer Part No. 5010 is ideal.