Reusable Polypropylene (PP) multi-combination Freezer racks have 24 places in a 6 x 4 Array for 0.5ml, 1.5ml - 2ml size micro tubes. These can maintain the temperature of less than 4°C for almost 3.5 hours at room temperature and are fully autoclavable. These racks can be used for transportation of biological samples, chemicals etc.. at a stable temperature for a long time. FROSTY MATE consistently cools samples and color changes dramatically, when the temperature of a rack containing samples reaches below 4° C, a clear visible color change from Yellow to Green can be seen. Reusable Polypropylene (PP) PCR Freezer racks have 96 wells / places in a 12 X 8 Array for PCR tubes. These can maintain the temperature of less than 4°C for almost 3.5 hours at room temperature and are fully autoclavable. These racks can be used for transportation of biological samples, chemicals etc.. at a stable temperature for a long time. FROSTY MATE consistently cools samples and color changes dramatically, when the temperature of a rack containing samples reaches below 4° C, a clear visible color change from Yellow to Green can be seen.