Borosil Reusable Heavy Duty Test Tubes are constructed from mechanically strong, low-extractable borosilicate glass. Thick, uniform walls, excellent thermal shock resistance & rounded bottoms mean these tubes can be used & reused without issue. Borosil Reusable Heavy Duty Test Tubes with Plain Ends comply with ISO/DIN 4142. Avail. in a variety of sizes ranging from 1mL (7mm x 60mm) to 170mL (38mm x 200mm). In collaboration with Borosil Glass Works, Foxx Life Sciences is proud to bring the outstanding quality of Borosil Type 3.3 Low-Expansion Borosilicate glassware to North America for the first time. Manufactured from the same USP Type 1, ASTM E-438/Type I/Class A borosilicate glass that North American scientists have come to trust, Borosil Laboratory Glassware offers unparalleled mechanical strength, clarity & reliability at competitive prices. And thanks to a unique annealing process, Borosil Glassware is stress-free & incredibly resistant to thermal shock.