The 407119 is a heavy-duty hot wire CFM thermo-anemometer designed to accurately measure air flow (CFM/CMM) and air velocity plus temperature in HVAC and ventilation applications. It features a telescoping probe that extends up to 3 feet (940 mm) long, ideal for use in ducts and ventilating systems, with air velocity measurements as low as 40 ft/min and a maximum range of 3346 ft/min. The instrument measures air volume in both CFM (ft³/min) and CMM (m³/min) simultaneously, with temperature measurement capability from 32 to 122°F (0 to 50°C), and displays air flow in two modes: instantaneous value or up to 20-point average. It includes a super large 1.4-inch LCD display, data hold and auto power-off functions, built-in RS-232 PC interface for optional data acquisition software, and comes complete with a 5.5-foot (167.6 cm) cable and four AA batteries. This instrument is ideal for HVAC technicians, engineers, and facility managers who need reliable air flow measurements for system commissioning, troubleshooting, and performance verification.