septa for 20ml headspace vials with screw caps wholesales--Headspace Vials for Sale Caps/septa, screw, headspace, 18 mm, silver, magnetic, PTFE. Caps/septa, crimp, headspace, 20 mm, small 5 mm opening, for 10 or 20 mL headspace vials, PTFE/silicone septa, 100/pk. Cap size: 20 mm AG8010-0424 $116.99 Cap Color Silver Cap Material Magnetic Cap