The Model 19 is a highly sensitive gamma R/meter employing an internally housed, 2.5 cm diameter by 2.5 cm   thick (1.0 x 1.0 in.) NaI detector. The measuring range is 0-50 v/h (0-5000 R/hr).   The cast aluminum instrument housing with its separate battery compartment and accompanying metal handle offers an industrial robustness and quality that promote long-lasting protection and instrument life. The front-panel controls include a rotary switch for selecting the five-decade range and instrument shut-off, audio on/off switch, a fast/slow response switch, and pushbuttons for activating the meter lamp, high-voltage display, battery test, and count reset.