Use this growler filler to fill your growlers, howlers or bottles cleanly and quickly, right from your tap! Double o-ring design insures a clean and secure fit. Fills from the bottom to reduce foam and CO2 loss. It is recommended to use Keg Lube or Petro Gel on the o-rings. This growler filler is not Compatible with Perlick faucets nor faucets from the Economy Tower, Walmart or Beermeister kegerators.