Cylindrical shaped drying tower has a 34/28 ground glass stopper.

Drying towers and columns are used to purify or dry common laboratory gases such as nitrogen or hydrogen. In typical laboratory use they are filled with a dry desiccant material such as KOH, activated molecular sieves, or calcium chloride and then the gas is slowly flowed through the tower. The stopper has a hole coinciding with a serrated hose connection sealed in the outer portion of the stopper neck and a second hose connection near the base of the cylinder. A hex base is sealed to the bottom of the tower for added stability.