This 18/5 25FT thermostat wire is a great choice for your indoor and outdoor low - voltage applications. With 18-Gauge and 5-conductors, it's CL2 and ETL compliant, having a temperature rating from -20°C to +60°C and a voltage rating of 150. The inner solid pure copper conductor and premium PVC insulator offer high conductivity and resist oxidation and corrosion. The high - quality PVC jacket makes it waterproof and durable, suitable for harsh outdoor conditions. It can be used for thermostat control, heating and A/C installations, doorbells, and more. Measuring 6.85 in. x 5.94 in. x 2.56 in. size and weighing 1.04 lbs. it's easy to handle. Manufactured by a professional company, it's strictly tested for long - term use. If you encounter any issues, you'll get a quick resolution within 12-hours.