9mm Autosampler Vials with Caps & Pre-slit Septum. 9mm Blue Plastic Screw Caps is suitable for: 9mm Short Thread HPLC Vials. Caps Material: polypropylene, size: 11.5*6mm, inner diameter: 9mm, with 6mm Centre Hole or Closed-Top. Color: usually blue, other colors are also provided, such as red, black, yellow, etc.