China economical 16mm cod reagent vials with round bottom 16mm Screw Neck COD Test Tube on Sale--Aijiren HPLC Vials 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 2. 12mL Clear test tube for