Wirelessly, this unit receives outdoor temperature and humidity via a solar powered sensor up to 200 ft away. Indoor temperature and humidity is picked up directly. (Two rechargeable AA batteries needed for the main station are not included.) Also 12 Hour time display. Wall hanging or Free standing. Displays Indoor & Outdoor Temperature (with min/max) and Indoor & Outdoor Humidity using any of 3 different display options. Indoor temp range 16 to 140 degF. Outdoor range -39 to 140 degF. Humidity range 20 to 95% indoors, 1 to 99% outdoors. Full instructions.