This pack of 50 heavy-wall borosilicate 3.3 glass test tubes has a 50ml capacity per tube. The uniform 2mm wall thickness provides superior thermal shock resistance, strength, and durability compared to standard-wall tubes, making them suitable for centrifugation, boiling, and open-flame reactions. Each tube measures 5.9" (150mm) tall with an outer diameter of 0.8" (24mm) and an inner diameter of 0.67" (20mm). The beaded rims are fire-polished for chip and crack resistance. The borosilicate glass is autoclavable with heat tolerances of: Strain Point 515°C, Annealing Point 565°C, and Softening Point 820°C.