#1 Training tool used by Colleges, Universities and Training Centers SuperHeat & SubCooling charging of R32, R454B, R410A and R22 Duct Calculator that calculates CFM of Metal and Flex Duct Access to approximately 100 free tutorials by scanning the QR code on the tool Pressure Drop and Sizing for - Rectangular Metal, Round Metal, AND Round Vinyl Flex This amazing tool performs every function needed by the HVAC professional. Including both SuperHeat and SubCooling of R32, R454B, R410a and R22; a Duct Calculator that calculates CFM, Pressure Drop and Sizing for - Rectangular Metal, Round Metal, AND Round Vinyl Flex. It's the only slide rule on the market that has conversion for Smooth Metal to Insulation Lined Metal. It also contains: Testing for Correct System Airflow for A/C & Heating for both electric and gas Pressure Drop Chart Wet Bulb Conversion Chart Troubleshooting Compressors Troubleshooting TXV's (TEV's) System Operating Diagnostics Capacitors - Laws & Practices OHM's Law Wheel and every Formula & Conversion needed For more information and to access over 100 Video Training Tutorials, visit our website SuperCool Slide Rule.