EISCO Volumetric Flask 25ml – Class A – 10/19 Polyethylene Stopper Borosilica… por | Jul 17, 2026Eisco Labs Borosilicate glass has the following heat tolerances: Strain Point -515°C | Annealing Point 565°C | Softening Point 820°C. The stopper is socket size 10/19, made of polyethylene, and is acid proof and autoclavable.