Conductor 18 AWG soft annealed solid copper per ASTM B3-90. PVC thermostatic insulation, temperature 60 degrees Celsius. Used for thermostat controls, heating and air conditioning installations, burglar alarm systems, intercom systems and doorbells. PVCinsulation UL13 for power limited circuit cable for other than plenum, riser, or tray uses and UL1581 approved.