Air gap faucets for Reverse Osmosis systems dispense water just like standard non- air gap faucets, but have the air gap built into the base of the faucet. Air gap faucets are designed to prevent backflow by incorporating a "backflow prevention" method called an "air gap".
Air gap faucets have 3 line connections - one for the drain, one for the pure water to dispense, and one for the waste water from the RO system.
Air gap faucets are required in some areas as a matter of local codes, not in other areas. You will need to check your local code to see if you are required to install an air gap faucet.