【2ml Vial Material】: 9mm Screw Thread Autosampler Vials are made of USP Type 1, Class A Borosilicate Glass with very low expansion coefficient,conforming to USP Type I and ASTM E438, Type I, Class A requirements 【9-425 Vial Dimension】: 2ml, 12*32mm, 9-425 screw top vials is 40% larger opening than standard narrow opening vials.