These flat bottom boiling flasks have full length outer 24/40 standard taper joints, but with shorter necks. Wall thicknesses are controlled to provide balance between thermal expansion and mechanical strength for greater shock resistance. The flat bottom boiling flasks are designed to ASTM E-1403. Adapter Cat. Nos. 8800, 8820, and 8825 are used to connect flasks with different size joints, thus allowing numerous combinations for diverse assemblies.