24PK Test Tubes, 85mL, 25x250mm - Rimmed - Marking Spot - Light Wall, 1.2mm Thick - Borosilicate 3.3 Glass

This 24-pack contains heavy duty borosilicate 3.3 glass test tubes with a 85mL (1.7oz) capacity and uniform 1.2mm walls. Each tube measures 9.8 inches (250mm) tall with an outer diameter of 1 inches (25mm) and an inner diameter of 23.8mm. The tubes accept stoppers with a bottom diameter of 20 to 22mm and a top diameter of 27 to 29mm. At 250mm tall and 25mm across these tubes are closer to boiling tubes than standard test tubes and require a rack sized to match. The rims are fire polished into a bead rather than cut. Fire polishing rounds the glass edge under heat and removes the microscopic flaws where cracking begins, producing a rim that resists chipping through repeated racking and washing and giving a stopper a defined seat. At 1.2mm the wall is matched to the larger diameters in this series so the tubes tolerate direct flame without a water bath. Borosilicate 3.3 glass withstands direct flame, high temperatures, and thermal shock, and the tubes are autoclavable for sterilization and reuse.