Borosil Bolt Neck Filtering Flasks shape is designed to impart maximum mechanical strength. They are blown in special molds to withstand the demands of the modern laboratory. The neck finish is developed for strength and to ensure a proper stopper fitting. Avail. in 50mL to 20 L capacity. 10L and 20L Flasks are in bottle shape. 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.