The Corning Pyrex 4965A-500 glass three neck distilling flask is a round-bottom flask with three necks suitable for general laboratory use. It is constructed of borosilicate glass for chemical, thermal expansion, shock, and heat resistance. The center neck has a vertical 24/40 standard taper joint and the two angled side necks are at the same height as each other with 24/40 standard taper outer joints to allow for insertion of items such as thermometers, stirrers, or drips. The flask is designed to be reusable and can be washed or autoclaved. The flask has a capacity of 500mL and dimensions of approximately 156mm height x 87mm outside diameter.

Flasks are glass or plastic containers for storing or collecting chemical samples or solutions in scientific laboratories. They come in a variety of sizes and shapes and are designed for a wide range of scientific processes. Erlenmeyer flasks, introduced by German chemist Emil Erlenmeyer in 1861, are shaped like a cone with a wide, flat base that narrows to a neck opening, which can be closed with a stopper or cap.

Corning manufactures consumable glass, ceramics, and plastic laboratory tools under the brands Corning, Costar, Cellgro, Pyrex, Axygen, Gosselin, and Lambda, among others. The company, founded in 1908, is headquartered in New York, NY.