This portable key-chain timer has a large, four-digit LCD that shows time remaining in hours and minutes. You can program it in the countdown mode from 20 hours to 1 minute. When zero is reached, an alarm sounds for 60 seconds or can be silenced manually. In the stopwatch mode it times from 1 second to 20 minutes, then repeats itself. The key-chain timer has a rugged ABS case, quartz crystal 0.01% accuracy and a 1½-year, continuous-use replaceable silver oxide battery. The timer includes a Traceable® certificate (issued by an A2LA-accredited, ISO/IEC 17025-certified lab), which documents traceability to N.I.S.T. standards. Dimensions (W x H x D): 1½ x 2 x ¾ in. Wt. ¾ oz.