These glass vials are the original design used in most autosamplers requiring traditional screw top vials. The vials are manufactured from Type I borosilicate glass. Vials are packaged 100 per shelf pack and 10 packs per case. Glass limited volume inserts are available with flat bottoms or springs. The black polypropylene screw caps can be purchased separately or preassembled. For quick and easy preparation, purchase vials and caps together in Convenience Packs.