Funnel, Sep, Squibb, 500mL, 4mm PTFE Stpk, #27 Stopper Neck with Detachable GL-14 TFE Drip Tip, PE Stopper. This unique separatory funnel is manufactured with a removable PTFE stem that virtually eliminates breakage normally associated with standard glass stem stopcocks. Made entirely of PTFE, the stem attaches directly to the glass stopcock without o-rings or other gaskets. Glassware equipped with this PTFE stem can survive repeated forceful strikes to the stem without breakage. Supplied complete with a PE or glass stopper of the listed size.