Kestrel 4100 Pocket Air Flow Tracker for HVAC Applications - FREE PRIORITY MAIL SHIPPING IN THE USA!! Regular price: $299.00 Sale price: $239.00 Kestrel 4200 Pocket Air Flow Tracker for HVAC Applications - FREE PRIORITY MAIL SHIPPING IN USA!! Regular price: $349.00 Sale price: $259.00 Need more information? Please feel free to contact us at 1-800-592-6940 - Ask for Extension 547 or Internet Sales.