The Ss Brewtech Whirlpool fitting attaches to the thermometer port, the recirculation port, or another 7/8" hole. Creates a nice whirlpool action that works perfectly with a trub dam to keep out most of the hop matter and other solids from your fermenter. Made from 304 stainless steel. The whirlpool fitting has a 1/2" MPT and comes with 1" x 1/2" bulkhead.