Hexagonal Hollow Stopper with Round End, 12/21, Borosilicate Glass

This hollow stopper is made from heavy-duty 3.3 borosilicate glass with a hexagonal-shaped top and round end. Features a 12/21 cone size. The stopper measures 1.55 inches in total length with a top measuring 0.6 inch long and wide. Autoclavable with superior chemical durability and thermal shock resistance. Heat tolerances include a Strain Point of 515°C, Annealing Point of 565°C, and Softening Point of 820°C. Suitable for sealing laboratory glassware with matching 12/21 ground glass joints.