Round-bottom flasks (also called round-bottomed flasks, Flasks, round bottom, or RB Flasks)having spherical bottoms are more resistant to fracturing under vacuum, as a sphere more evenly distributes stress across its surface. Because of the spherical bottom, cork rings are needed to keep the round bottom flasks upright. When in use, round-bottom flasks are commonly held at the neck by flask clamps on a stand.
The flasks are usually used in heating or boiling a liquid, in distillation as distilling flasks and receiving flasks for the distillate,used as the distilling flasks in rotary evaporators.
Laboy glass flasks are heavy wall designed,made by hand-blowing to ensure uniform wall thickness, made of high-quality borosilicate glasss and annealed at 800 degree Celsius ,can be heated directly in an open flame and can withstand typical laboratory thermal variations in chemistry processes like heating and cooling.