These 1L PYREX heavy duty boiling flasks provide increased mechanical strength. The flask features walls which are 25-30% thicker than the standard version. O.D. dimensions have not been changed. They have full length outer 24/40 Standard Taper joints, but with shorter necks. The normal working temperature for PYREX boiling flasks is 230°C. Adapter Nos. 8800, 8820 and 8825 are used to connect flasks with different size joints, thus allowing numerous combinations for diverse assemblies.