The culture bottles are moulded from DURAN® borosilicate 3.3 Type 1 glass, and are ideal for the preparation of media or culturing of microorganisms. The bottles comply with ISO 4796-2 and feature a narrow conical unground neck for use with rubber stoppers, cotton wool plugs, sterile closures, polyurethane foam stoppers, or silicone culture plugs. Suitable for autoclaving at 121 or 134 °C or dry heat sterilization.