Long Reach Faucet with Air Gap and 1/4" O.D. water line fitting.
Has connections for three lines used with "air gap" type Reverse Osmosis installations.

Air Gap style faucets are required by most "plumbing codes", and are standard with Microlline Reverese Osmosis systems.
Some other brands do not use this type of faucet.
Also, many installers prefer using a Non-air Gap style of faucet.
In such installations the drain line does not run up to the faucet, but is connected directly to the drain clamp under the sink.