The FIRMAN T07571 generator has 11%–14% total harmonic distortion (THD) at full load. Sine wave quality: Fairly high distortion; not a clean sine wave. Typical appliances: Generally suitable for many household appliances and power tools. Sensitive electronics: Not ideal for sensitive equipment or some UPS units, which may reject the power. For comparison, a generator with less than 5% THD is preferable for sensitive electronics; under 3% is even better.