Borosil Reusable Heavy Duty Culture Tubes are constructed from low-extractable, mechanically strong borosilicate glass. Supplied with PTFE-lined Polypropylene Screw Caps, tubes are easy to seal. Flat bottoms and ultra-high clarity. Ideal replacement for Biju/Bijou, McCartney, and culture or media bottles. Borosil Heavy Duty Culture Tubes with Flat Bottoms are available from 5mL to 50mL. Also available in Light-Blocking Amber (Product Family 9911). 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, and reliability at competitive prices. And thanks to a unique annealing process, Borosil Glassware is stress-free and incredibly resistant to thermal shock.