http://www.casio.com/products/Watches/Classic/F91W-1Water Resistant
Micro Light
Daily Alarm
1/100 second digital stopwatch
Measuring capacity: 59’59.99”
Measuring modes: Net time, split time, 1st-2nd place times
Hourly Time Signal
Auto Calendar
12/24 Hour Formats
Accuracy: +/-30 seconds per month
Battery CR2016
Approx. battery life: 7 years
Module 593
Size of case / total weight
38.2 x 35.2 x 8.5mm / 22g
The F-91W has a 1/100 second stopwatch with a count up to 59:59.99 (nearly one hour) and measuring modes of net time, split time, and 1st and 2nd place times. There are the options of an hourly time beep and a single daily alarm. It has an automatic calendar, although auto-adjustment for leap years is not supported, as the watch does not record the year.[2] The watch is claimed to be accurate to ±30 seconds per month[2] (6 minutes per year).
The watch is powered by a single CR2016 lithium button cell, which Casio claims will last approximately seven years (assuming 20 seconds of alarm and one second of light usage per day). The watch case measures 37.5 × 33.5 × 9.5 mm and weighs 20 g. The manufacturer's module number for this model (stamped on the stainless steel rear of the watch case) is 593. The watch front is marked WATER RESIST.[2] The instructions state that water resistance is limited to splashes, rain, etc., so the watch should not be worn while swimming.
http://en.wikipedia.org/wiki/Casio_F91W
