Borosil Amber 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 handle and seal. Flat bottoms and ultra-high clarity. Ideal replacement for Biju/Bijou, McCartney, and culture or media bottles. Amber protects from light between 300nm and 500nm. Borosil Heavy Duty Culture Tubes with Flat Bottoms are available from 5mL to 50mL. 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.