The Extech AN500-NIST Hot Wire CFM/CMM Thermo-Anemometer's sensor technology delivers with major improvements in durability and ATC (Automatic Temperature Compensation) for accurate in-duct measurements for air velocity with changing air temperatures. The included ATC Telescoping Probe ensures that the Extech AN500-NIST is able to take measurements that are in the center of the duct, even if it is out of reach. The ergonomic directional handle and anti-rotation sensor confirms that the probe and airflow directions are aligned for confident readings. The Extech AN500-NIST also comes with a 100 V - 240 V AC universal adapter with four plugs, six batteries, and a hard carrying case.