Low pressure (7 psig max) medium wall chromatography column with reservoir. Columns feature a PTFE insert with a locknut that attaches the flow control valve to the column. Top closure is a GL-45 thread for a positive connection. An all PTFE-valve and exposed drip lip eliminate tip damage. Columns include bottom valve assemblies, GL-45 caps, PTFE inserts, lock-nuts, O-rings, and flow adapters.