This drinking water faucet has a single standard 1/4" compression fitting at the base which allows it to hook to virtually any standard water treatment system. It also has the required fittings to hook up the drain air gap. Fits: Ametek Reverse Osmosis Systems American Plumber Reverse Osmosis Systems US Filter Reverse Osmosis Systems Culligan Reverse Osmosis Systems Pentek Reverse Osmosis Systems And many, many others... This unit has a 3" shank and is NSF listed and certified to NSF/ANSI Standard 61 section 9.