These round-bottom flasks have four [ST] outer joints

Available with heavy or standard walls. Heavy wall flasks feature walls that are approximately 30% heavier than standard wall flasks.

The outer joints are tooled with reinforcement rings (full-sized joints only) for added strength and stability. Necks are vertical unless noted otherwise. Two of the side necks are in-line with the center neck. The third side neck is placed in front of the center neck. Fabricated from borosilicate glass.