This digital stopwatch features a jumbo display, with digits 3/8" high, showing minutes, seconds, and 100ths of seconds. Used as a stopwatch, it times up to 30 minutes. It has time-out and accumulation features, as well as a start/stop reset button. When it is not in stopwatch mode, it serves as a compact digital clock, showing hours, minutes, seconds, a.m. or p.m., day, and date. It continues to keep accurate time even when you are using the unit as a stopwatch. So, whenever you leave stopwatch mode, the unit will show the correct time of day. It runs on a single AA battery (included), which will last more than a year. The unobtrusive black high-impact plastic housing is only 3.5" x 2.4" x .63" thick and the unit weighs only 2.5 ounces. One-year guarantee by manufacturer.