Closures for 8-425 screw thread vials These closures have a 8-425 thread and fit all our 8mm screw cap vials. The open-top caps are for use with 8mm septa 9mm Screw Caps and Septa Assembled caps compatible with robotic autosamplers Our 9mm closures have the profile of a crimp or snap cap so are compatible with robotic autosamplers.