This amazing tool performs every function needed by the HVAC professional. Including both SuperHeat and SubCooling of 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. The item "SuperCool Slide Rule by SuperCool Slide Rule" is in sale since Thursday, September 9, 2021. This item is in the category "Pet Supplies\Cat Supplies\Other Cat Supplies". The seller is "buyerspath" and is located in Hamden, Connecticut. This item can be shipped worldwide.