This page opens with the timer already set to 1 minutes. Press Start or hit the spacebar and it begins; when time is up the alarm rings and the disk blinks. You can always drag the disk to a different time.
For short bursts, a shape beats digits. A 1-minute disk tells you what's left in one glance, so you keep moving instead of checking a clock.
A 1 minute timer suits short and sharp things: a plank set, brushing teeth, or a one-minute speech drill.