These round-bottom flasks have angled side necks and [ST] outer joints

The outer joints are tooled with reinforcement rings (full-sized joints only) for added strength and stability. The flare-out directly below the center joint facilitates cleaning of the flask and enables stirring blades to be easily removed. Fabricated from borosilicate glass. Heavy wall flasks feature walls that are approximately 30% heavier than standard wall flasks.