Roll of 20000 Labels. Printable, water-indicating polyester/paper laminate labels for thermal transfer printers. For use in locations where clear evidence of water intrusion is desired for controlling invalid warranty claims, failure analysis, design assistance or trouble shooting (service and repair). This material is designed to permanently change colors (white to red) when water based solutions contact the edge of the label. It will withstand high heat and humidity environments without false indication appearing. Please Note: This material is UL recognized with its respective ribbon. See the "Recommended Ribbon Series" for the appropriate ribbon to use.