Nalgene®. The accuracy of standard glass flasks combined with the break resistance of plastic. Polypropylene with polypropylene screw cap. Graduated and leakproof. Gravimetrically calibrated individually TC/TD at 20°C. Printing is durable; won't wear off. Guaranteed to meet the Class B accuracy requirements of ASTM E288 and ISO Standard 384. No meniscus to confuse readings. Oval marking spot. Cat.No. 7-4000-0200 has additional line at 203-ml level for BOD and DO determinations. Can be autoclaved, but accuracy will be affected. Before autoclaving, set closure on top of the container without engaging the threads.