Timex Ironman Classic 30 - Matt Damon - Stillwater
The Timex Ironman Classic 30 is available in several color variations, but the watch worn in the film seems to be the version with an all black case and red details. The red Timex logo seems to be removed by the movie's production department, perhaps because it is not an official product placement.
The 30 is named after the lap times of 30 laps it can record in a 100-hour stopwatch mode. Timex also offers other Ironman models that can record for example 50 laps or 100 laps.
See an overview of other Ironman lap watches on this website here.
Other features of this watch are 24-hour countdown timer, 3 daily, weekday or weekend alarms, 24-hour military time mode, 2 time zones, day, date & month calendar and an Indiglo light-up watch dial. This Ironman watch is water resistant to 100m (330ft), suitable for swimming and snorkeling, but not diving.