A plain countdown timer: set the minutes, press start, and watch it run down with an alert at zero. Useful for exams, drills, presentations, workouts and cooking — anywhere a visible remaining time keeps a room on track.
Countdown or elapsed?
A countdown answers "how long left", which is what an audience needs. Elapsed time answers "how long so far", which is what a stopwatch is for. Running the wrong one is a common and avoidable irritation — see timing exams and drills.