Pura's nifty AddOn-3 is a three-gallon-per-minute system, each designed as a stand-alone UV unit or as a convenient addition to an existing drinking water unit. These are compact, easily installed systems that are trouble free and easy to service. They have no filters to change and require only an annual lamp change. The Add-On units are fitted with John Guest type 3/8" push-in quick connect fittings. Simply push your 3/8" plastic or polypropylene tubing into the fitting for a tight, leak-free seal. Model Pura Add on 3 (UV003) Suggested Use Post purifier for larger reverse osmosis or other drinking water system. Dental offices. Small water vending systems. Max Flow Rate 3 Gallon per minute (GPM) Replacement Lamp Size # 20 Lamp Power Usage 22 Watts Replacement sleeve # 20 Voltage 12 Height 22.5" Cap Diameter 3.5" Tube Connection 3/8" Quick Connect