This innovative line of plastic test tube racks are shipped flat in order to reduce shelf space and then simply snap together for use. The special design allows all samples to be incubated at the same temperature. These racks can be used in freezers without deforming or going brittle. They will not rot, rust of deform. Alphanumeric markings are molded into the racks to provide easy test tube identification. They are available in assorted colors for sample coding or aesthetics. Polypropylene (PP) Autoclavable Non-floating in water baths Stackable when empty