The Triplett AM500 Hotwire Anemometer uses a strong and precise airflow and temperature sensor to provide very accurate readings. The compact telecsoping probe head is ideal for ductwork. This micro-processor based design includes ATC (Automatic Temperature Compensation) and allows for accuracy on low flow (30ft/min) applications where traditional vane anemometers do not. It is a must have for any HVAC Engineer or Technician. Complete with telescoping probe with magnet,O-ring marker, hard carrying case and four 1.5V AAA - 1-year warranty. Comes with Certificate of traceability to NIST Standards. Please add 11 business days lead-time for the NIST calibration process