Product Description : Round-bottom flasks (also called round-bottomed flasks, Flasks, round bottom, or R B Flasks) are types of flasks having spherical bottoms used as laboratory glassware, mostly for chemical or biochemical work.They are typically made of glass for chemical inertness; and in modern days, they are usually made of heat-resistant borosilicate glass. There is at least one tubular section known as the neck with an opening at the tip. Two or three-necked flasks are common as well. Round bottom flasks come in many sizes, from 5 mL to 20 L, with the sizes usually inscribed on the glass. In pilot plants even larger flasks are encountered.