Kimble 60942A-40 Borosilicate Glass Cylindrical 40mL Sample Vial, with Black Phenolic Polyseal Cone Closure Attached (Case of 72) Composed of KIMAX KG-33 borosilicate glass; meets the requirements for ASTM Type 1, Class A and USP Type 1 Glass and combines a low coefficient of expansion with a very high chemical resistance Vial top has a screw thread finish Attached closure has solid top Cylindrical shape provides solid balance Flat bottom facilitates free-standing capability