Adjustable bed chromatographic column used for recycling, ascending or descending applications allowing for quick and easy adjustment of the PTFE plunger. The Por. C (25-50m) glass disc gives rapid flow with a minimum of mixing. Pressure tight to 3.515 Kg/cm2 (50 psi) at room temperature or slightly below. PTFE plunger available with PTFE or FETFE O-Ring seals.