Microwave power density instrumentation can be classified according to intended use, the type of detection system employed, and the type of information displayed. The intended use is subdivided into desirable features for laboratory instruments and survey instruments; method of detection is broken into thermal and electrical detection; and the information display category is divided into quantitative and qualitative display. Several commercial microwave power density meters which have been tested by the Division of Electronic Products, Bureau of Radiological Health, are compared according to the following criteria: accuracy, sensitivity, dynamic range, reliability, ease of measurement, thermal stability, battery life, and cost. (Author)