This chromatography Column is a glass tube with joint at Top and PTFE stopcock at bottom, used to purify individual Chemical compounds from mixtures of compounds. It is often used for preparative applications on scales from micrograms up to kilograms. Laboy glass are all made of high-quality borosilicate glass and made by hand and-blowing to ensure uniform wall thickness. Since the chromatography column is used with positive air pressure, it is highly recommended that operator uses column behind a safety shield.