Use for liquid scintillation counting, gamma counting, chromatography, sample storage, and culturing Made from 51 expansion borosilicate glass conforming to USP Type I and ASTM E438 Type I, Class B requirements Each vial measures 2.25" (57mm) tall, and has an outer diameter of 1.1" (28mm) Vials and screw-top caps are preassembled and shrink wrapped into trays Superior chemical durability and heat tolerance. Designed for use in professional laboratories, but is an ideal choice for science classrooms and household use. Clear Scintillation Vials with a 20mL capacity are ideal for use in liquid scintillation counting, gamma counting, chromatography, sample storage, and culturing. The high quality 51 expansion borosilicate glass construction has excellent optical quality and meets ASTM E438 Type I Class B and USP Type I standards. Vials have flat bottom for maximum stability. Screw top caps are manufactured from high purity polypropylene with a polyurethane liner, and come presassembled onto vials. Each vial with cap measures 2.25" (57mm) tall, and has an outer diameter of 1.1" (28mm). Entire pack of 100 vials is shrink wrapped into its tray.