Borosil® Reusable Heavy Duty Test Tubes are constructed from mechanically strong, low-extractable borosilicate glass. Thick, uniform walls, excellent heat resistance, & rounded bottoms mean these tubes can be reused without issue. Each tube is graduated in metric units, & comes with a standard taper glass stopper. Borosil® Reusable Heavy Duty Test Tubes with Graduations & Glass Stoppers are available from 10mL (17mm x 160mm) to 100mL (34mm x 210mm). In collaboration with Borosil Glass Works, Foxx Life Sciences is proud to bring the outstanding quality of Borosil® Type 3.3 Borosilicate glassware to North America for the first time. Manufactured from the same USP Type 1 borosilicate glass that North American scientists have come to trust, Borosil® Laboratory Glassware offers unparalleled mechanical strength, clarity, & reliability at competitive prices. & thanks to a unique annealing process, Borosil® Glassware is stress-free & incredibly resistant to thermal shock.