We supply autosampler vials, Headspace vials and COD vials at factory price. 1. PTFE Septa for 16mm test tube Closures, White Screw Polycarbonate cap, Closed-top. 2. 12mL Clear test tube for Water Analysis Round Bottom, 16x100mm Mid borosilicate. Features. 1. 12mL Clear test tube for Water Analysis Round Bottom, 16x100mm Mid borosilicate