The PMD74 is a microwave leakage detector from Pyle. This device never needs calibration and allows you to accurately and precisely measure the amount of radiation emitting from your microwave. Measures from 0 to 9.99 mw/cm2. The PMD74 will automatically signal a warning beep and LED flash if the detected radiation is above safe levels (5 mw/Cm2). Make sure your microwave is functioning properly and get piece of mind with the PMD74. On a 9V battery, the PMD74 operates for one year.