Reusable test tubes are made from KG-33 glass tubing with a sturdy lip and uniform wall thickness for maximum heat transfer and chemical resistance. Durable white ceramic enamel marking spot on each tube. Reusable. Designed from ASTM Specification E982, Type I requirements. 25 x 200 (O.D. x Length). 75mL Overflow Capacity. 192-Each/Case. Kimble® #: 45042-25200.