Polypropylene Test Tube Racks – 40x 20mm Holes, Blue-Large capacity racks. Autoclavable at 121C for 20 mins. Can be used dry, wet, in water baths. Will not float. No restrictions down length of rack so all samples will be incubated at same temperature. Can be used in freezers without deforming or going brittle. Will not rot, rust or deform. Alpha numerical grid reference on top tier for easy identification of samples. Colour coded for batch work. Stackable when empty.