Oxygen Free Tri Clamp Dry Hopper 3"TC This dry hopper allows you to dry hop or add any additions to your beer without introducing oxygen and oxidizing the beer. It also allows you to make additions to your beer fermenting under pressure without having to release the pressure. This helps stabilize your fermentation schedule resulting in better repeatability with batches, healthier fermentation, and less oxidation. This dry hopper works by containing the addition inside of a extension tube and purging out the oxygen before dosing. By equalizing the pressure inside the sight glass and fermenter, you can add anything to your beer without degassing or depressurizing. With the included prv and corny gas post, you will be able to completely purge the chamber before dry hopping. We know a lot of people have a 2″ TC port or 1.5"TC ports with fermentors, so you can choose a 3" x 2" TC cap reducer or a 3" x 1.5"TC cap reducer and extra clamp and gasket to make the dry hopper compatible.