Extechs vane type 451 series anemometers come with multi‑selectable units, to insure you get measurements in your preferred unit of measure. These meters either come with a remote or integral vane. The integral vane has a built in vane wheel, while the remote vane is ideal when having to reach into an air duct or other HVAC application. Some of the meters have the datalogging feature, which lets you log your measurements as you take them in the field, for further analyzation.