9mm Screw Top Vials. 9mm screw thread vials have a 9-425GPI thread and the closure is dimensionally equivalent to 11mm crimp cap vials. This means that they can be used in any autosampler that use 11mm crimp vials. 9mm screw caps have an advantage over 11mm crimp caps because 9mm screw caps can easily be applied and removed by hand and be reused.