Six range indicators (1, 2, 4, 8, 16, and 32 mR/hr) clearly display an increase or decrease in radiation levels. The alarm can be set at any of the six levels by a front panel, screwdriver-adjustable control. Both the visible and audible alarms, or just the visible alarm, can also be set from this panel. The light for each level goes on when the radiation intensity reaches that level, and goes out when the rate drops below the level. This permits instant radiation-level recognition not readily distinguishable on meter-type instruments.