This specification provides the standard appearance, capacity, design, and dimensional requirements for eight types of multiple neck distilling/boiling glass flasks for laboratory use. Flasks, which shall be made of borosilicate glass conforming to specified maximum residual thermal stresses, are available in the following types: Type I, standard taper necks of equal height; Type II, three tooled necks of unequal height; Type III, three standard taper necks of unequal height; Type IV, three standard taper necks of equal height; Type V, three tooled necks that are angled; Type VI, three standard taper necks that are angled; Type VII, two standard taper necks of unequal height; and Type VIII, two standard taper necks that are angled.