Ambient Weather WS-1000-BTH Replacement Thermo-Hygrometer-Barometer for WS-1000, WS-1200 Weather Stations Ambient Weather WS-1000-BTH Replacement Thermo-Hygrometer-Barometer for WS-1000-WiFi, WS-1001-WiFi, WS-1200, and WS-1200-IP Observer Weather Stations. Measures indoor temperature, humidity and barometer This is a replacement part and intended for wireless communication to the Observer Series. Requires 2 X AAA batteries (not included)