3mm Screw Autosampler Vial. The size of the 4ml autosampler sample vial is 5x45mm, with 3-425 GPI threads, and can hold up to 4ml samples. Sample vials are preferentially used for instruments of the following manufacturers: Rated 4.7 /5 based on 420 customer reviews. 3mm screw vial 4ml hplc vial 4ml screw vial.