These 250mL Pyrex® low actinic flat-bottom boiling flasks have full length outer 24/40 ST joints, but with shorter necks. Low actinic stained glass provides protection for materials sensitive to light. The protective color is an integral part of the flask, which retains the mechanical strength, chemical stability and thermal resistance of Pyrex® labware. They are manufactured from No. 7740 borosilicate glass. 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.