Sizes: 27.5 x 95mm and are packaged 100 vials per box. EPA vial caps Both injection-type and solid storage caps are available for these vials. EPA vials are 24mm screw top and suitable caps are sold separately. EPA caps are pre-assembled with a variety of septa, to suit a number . common use headspace gas chromatography with PTFE septa . Use of headspace–gas chromatography–ion mobility. 2021 - 04 - 27.