Description. Use Thermo Scientific™ SureSTART™ 9 mm Screw Caps with screw vials that have a 9 mm opening, including our SureSTART 2 mL Glass Screw Vials, 2 mL Gold-Grade Glass Screw Vials, Total Recovery Glass Screw Microvials for <2 mL samples, 1.7 mL High Recovery Glass Screw Vials, and Glass Screw Microvials for <2 mL samples (Level 3).