Small and light enough to go anywhere, yet sensitive enough to detect minuscule amounts of gamma, beta or X-rays. Excellent for scanning lab work areas and clothing, for traces of radioactivity after clean up, or as a personal monitor in areas of potential radiation exposure. Useful in school labs for geology and science projects. One button operation, can be used by untrained personnel. Uses a Geiger-Mueller tube detector. The meter registers 0.1 to 10 mR/hr, (milli-Roentgen), on a unique dual scale. Audible clicking will increase with the amount of background radiation. Beeping begins at 20 mR/hr, increasing in frequency in proportion to the radiation level. Powered by a 9 volt battery, included, which lasts 50 hours at normal background levels. 6 5/8" x 3 1/4" x 1 3/8".