This handy accessory allows you to fill growlers from the bottom which creates less foam. The Stainless Steel end and double o-ring seals provide a good tight seal to the inside of the faucet preventing messy leaks. Heavy duty construction means this will last far longer than similar items which are basically just a hose shoved into the faucet. Fits Perlick 500 series faucets. (Too big to fit 600 series)