These Pyrex® heavy duty boiling flasks provide increased mechanical strength. The flask features walls which are 25-30% thicker than the standard version without changing dimensions. They have full length outer ST joints, but with shorter necks. The normal working temperature for Pyrex® boiling flasks is 230°C. Adapter Cat.Nos. 1-8800, 1-8820 and 1-8825 are used to connect flasks with different size joints, thus allowing numerous combinations for diverse assemblies.