Premium Class B Borosilicate Burette Capacity = 100mL with 0.2mL Graduations and 0.2mL Tolerance Glass Key stopcock requires lubrication but offers the smoothest, most authentic control. Designed to store liquids in the laboratory, but can be used in the home as well -- or even for beer and wine making. Please clean thoroughly before first use. Premium borosilicate 3.3 glass burettes Eisco Labs Borosilicate glass has the following heat tolerances: Strain Point -515°C | Annealing Point 565°C | Softening Point 820°C.