AquaFlex ® PRO-4 Tank is the tank number for a standard tank that is used on many, many reverse osmosis systems. Identifying the tank will not identify the RO system or replacement filters. Most systems using this Aquaflex Saniflex tank used standard size replacement filters and reverse osmosis membranes. For help matching up your system see:
Standard Reverse Osmosis systems using standard size replacement filters and RO membranes.
While the tanks in the help file may look different from the AquaFlex PRO-4, look to match the described configuration of the filters. The systems shown are using other generic tanks in place of the AquaFlex PRO-4.