This is a modified chromatography column,with lower 24/40 joint and hose connections for vacuum. The pore diameter for the sealed in glass fritted is from 20 to 35 ?m. Laboy glass are all made of high-quality borosilicate glass and made by hand-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.