Davis Sonic Anemometer 
Measure wind with no moving parts. Use with a Sensor Transmitter or an EnviroMonitor Node, or as a replacement anemometer for wireless and cabled Vantage Pro2.
The Davis Sonic Anemometer has no moving parts – it measures wind speed and direction with electro-acoustic transducers that send sonic pulses back and forth. The time it takes for the pulses to travel from one transducer to the other is affected by the movement of air. Speed and direction can then be calculated, with calibration for air temperature. The Sonic Anemometer has its own solar panel that charges an internal battery. It can be used with an EnviroMonitor Node, or as a replacement anemometer for your Davis weather station. It can also be installed in a Sensor Transmitter to create additional wind stations when reporting to WeatherLink Live.
Solar-powered with battery backup. Includes mounting hardware, battery, aligning tool, and 40 ft (12 m) cable.
Works with Sensor Transmitter (#6332 or 6331) or EnviroMonitor Node (#6810). (When using with an EnviroMonitor Node, use an RJ Connector Node Adapter.)
Quick Guide (pdf)
Owner's Manual (pdf)