These 15×100 mm PYREX round bottom glass test tubes are useful for the handling of sputum specimens. Digestion, shaking, neutralizing and centrifuging can be performed in one container. They are also useful for other clinical and microbiological tests. Black Screw caps resist the effects of temperature and steam. These tubes have a black polypropylene GPI 38-400 threaded cap with a Polytetrafluorethylene (PTFE) liner. This is the best branded test tube which ideal for sample keeping, and laboratory use. Brand: Pyrex, Origin: China, Supplier: Labtex Bangladesh.