1.5" Tri Clover Inline Sight Glass. Made of 304 stainless steel. Includes silicone seals and is easily taken apart for cleaning. One popular application for the 1.5" tri clover sight glass is to attach a cap to one end and then clamp it to the dump valve on a conical fermenter. Do this after dumping all your trub, then open the the dump valve and allow your yeast to settle into the tube.  Makes a great yeast collection cup.