Target Screw Thread Glass Vials, 2 mL, Clear I-D Vial (graduated to write-on patch), 33 expansion. Industry's original wide opening Target 2 mL, 12x32mm vials. Manufactured of highest quality borosilicate glass. Our I-D vials with write-on patch have graduations at 0.5, 1.0, and 1.5 mL.