Extech 407119 Heavy Duty CFM Hot Wire Thermo-AnemometerExtech 407119 Heavy Duty Hot Wire CFM Thermo Anemometer Heavy Duty Hot Wire CFM Thermo Anemometer Accurately measures Air Flow (CFM CMM) or Air velocity plus F C Temperature Using the telescoping probe that extends up to 3ft 9940m) long Key Features: Air velocity measurements as low as 40ft min Telescoping probe is ideal for use in ducts and ventilating systems; extends up to 3ft (940mm) long Measures air volume in CFM (ft3 min) and CMM (m3 min) plus