VWR disposable culture tubes are resistant to chemical attack and weathering. Manufactured from Type I, Class b borosilicate glass, each tube is heat-treated at temperatures exceeding 500°c (932°f) immediately before packing, which eliminates contamination, increases strength, and reduces breakage. Tubes exceed USP Type I specifications. Tubes feature well-rounded bottoms and fire-polished tops free of rough edges. Dimensional specifications of these tubes are rigidly controlled for reliable, uniform results. Tubes are clean-sealed in a convenient dispensing package to keep them free from dust and other particulate contamination. Tube 47729-566 is also known as a Durham tube. Contents will not leach out and contaminate solutions. Borosilicate glass construction prevents pH change in laboratory tests.