Sterile, skirted transport vials are made of Polypropylene-Copolymer making them chemical resistant for most solvents, bases and acids. The blue screw caps feature continuous, 1.5 turn threads that assistin securing the caps while keeping it easy to open and close. Quality control protocols include gravity and vacuum chamber testing to ensure that the seal integrity is maintained. Not autoclavable. 25 vials in a package and the case contains 500 vials.