For positive vial identification numbers and letters are molded into each holder's upper surface. Designed to hold 1.2, 2.0 and 5.0 mL sizes of Nalgene cryogenic vials. Autoclavable; solid construction and rubber feet make it stable on the bench top. Stackable when empty to save space. 50 Place Holders measure 197 x 102 x 28 mm high; 25 Place Holders measure 197 x 102 x 22 mm high.