Microscale, single-neck, round-bottom reaction flask

The top joint is a combination cap, thread and [ST] joint to accommodate and seal other microscale apparatus. The O.D. of the top joint has an external thread to facilitate an o-ring and open-top phenolic cap. The internal or I.D. at the top is a ground outer joint. This type of connection eliminates the need for clamps while offering the positive leak-tight seal of ground glass. Fabricated from borosilicate glass.