The Geiger measures beta, gamma, and x-rays. With each radiation event a red light flashes and a beeper sounds. (The beeper can be muted.) A cable and software for IBM PC-compatible computers is available. The Geiger's software expands monitoring and readout capabilities. A translucent label allows you to see the Geiger tube, which fluoresces (gives off light) in a dark room with an elevated radiation level. The Geiger is a low-cost instrument designed for schools and individuals. Specifications: Sensor: Glass Geiger-Mueller detector detects Beta, Gamma, and X-rays. Sidewall density 50 mg/cm2 plus 15 mil Lexan window. Operating Range: 0-420,000 CPM. Count light: Red LED flashes with each count. Beeper: Chirps for each count (can be muted). Outputs: Dual miniature jack provides counts to a computer or data logger. Submini jack provides audio output to an external earpiece, amplifier, or tape recorder. Power: One 9-volt alkaline battery. Typical battery life is 2000 hours at normal background radiation levels. Size: 150 x 80 x 30 mm (5.9 x 3.2 x 1.2 inches). Weight: 200 g (7 oz.) including battery. Optional Software: IBM PC compatible on 3.5-inch floppy disk. Displays current CPM and average, maximum, and minimum over a 24 hour period. Graphs counts per minute over 8 hours. Provides an audible alert at a user-adjustable level. Saves data for each day in a comma-delimited file compatible with spreadsheet and database software. Optional Cable: 6 feet, connects to 9-pin PC serial port (25-pin adapter available). Optional: STAND Optional: Carrying Case