This pack of 10 borosilicate glass tubes measures 20 inches in length with a 0.25-inch (6mm) external diameter and 3mm internal diameter. Using safe and appropriate heating methods, the tubes can be shaped to suit specific laboratory needs. The borosilicate glass is autoclavable with superior chemical durability and thermal shock resistance. Heat tolerances include a Strain Point of 515°C, Annealing Point of 565°C, and Softening Point of 820°C.