This value-priced pack contains five of our Erlenmeyer flasks, ranging from 50 ml to 1000 ml. Each one in this set is made of high-quality GG17 borosilicate glass that can be heated directly in an open flame. Low coefficient of thermal expansion means this glass is capable of withstanding thermal shock. Use for mixing and heating. The included graduations (lines) are approximate and not intended for accurate liquid measurement.