The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) establish industry standards and certify product performance. AHRI’s certification programs use technical standards based on sound engineering practices to rate the efficiency of HVACR equipment as well as many other product attributes. Petra Engineering Industries Co. Air to Air Packaged Unit product range is certified by AHRI to AHRI 340-360 which means they are listed in the AHRI Directory of Certified Product Performance after successfully meeting stringent standards for product performance.