Electronic quartz movement accurate to +/- 0.5 seconds per day. LCD is 8mm high, with resolution in one second intervals. Counts up or down for 100 hours. In the count up mode it can be used as an addition timer. In the count down mode, a unique feature lets you know how much time elapses after the alarm sounds. Memory allows repetition of a frequently used setting. At the flip of a switch, clock displays the time of day. Clips onto pocket, stands alone, or attaches to any metallic surface with built-in magnet. Compact case weighs 2 oz. Measures 2.5" x 2.3" x 0.6". 1.5 volt button cell battery included.