Avanti Designer Kitchen Bar Sink Reverse Osmosis RO Filtration Drinking Water Faucet - NSF certified, built-in Air Gap, ceramic disk, lead-free - RF888A-BN Brushed Nickel NSF / ANSI 61 certified - safe drinking water system components for cold water applications only premium designer drinking water faucet  Made in Taiwan built-in air gap to prevent backflow of sewer water from entering RO system via drain line quarter-turn single lever with precise flow control and no-drip 360-degree swivel spout; lead-free solid brass and 304 stainless steel construction with long-lasting ceramic disk cartridge fits opening between 7/8 and 1-1/4; fits countertop up to 2" thick; connected with 1/4 drinking water supply tube (not included); for 3/8" supply tube, a quick-connect adapter (ASIN B0796JNK4Z) is needed and sold separately