Quickly change tube sizes with this adaptable polypropylene rack. Open the iris with a turn of the knob or directly insert a tube into the opening. Holds up to 12 similar size tubes. Imprinted references for easy identification. Generously-sized handles for easy transport. Accepts tubes from 15mL to 50mL (diameter of 16mm - 30mm). No assembly required. Not recommended for cleaning in autoclave. Measures 194 x 140 x 51mm.