Extech hd 300 anemometer extech hd 300 p the extech hd 300 anemometer gives measurement and simultaneous display of air current in cfm cmm or air speed and the environment temperature in addition it possesses an ir thermometer and a target laser for contactless measurement of the temperature the surface dimensions are adjustable and are stored in the hd 300 till the next switching is saved p extech hd 300 anemometer