18/6 Class-2 Thermostat wire has 0.015-Inch white PVC jacket to withstand harsh environmental conditions. The annealed bare copper cable has 0.006-Inch PVC insulation that resists electrical leakage and offers protection against environmental threats. It has voltage rating of 150-Volt AC. This wire has outside diameter of 0.186-Inch. It withstands temperature range of -20 to 60 deg C. It is suitable for use with heating and air conditioning equipment, doorbells as well as other low-voltage applications. This 250-ft wire comes in a spool. Cable is UL/ETL listed, RoHS/OSHA compliant and meets NEC standards.