Name: Breath Pacer - Paced Breathing Timer
Author: RiversideArt

Breath Pacer guides slow breathing on your wrist. Choose coherent breathing (5 seconds in, 5 out), box breathing (4 in, hold, out, hold), 4-7-8, or a 4 in and 6 out relax pattern, and a session length. A circle grows and shrinks with the breath, and a short buzz marks each change.

It is a pacing aid, not medical advice.

Controls:
Select or tap: start or pause
Down: next phase
Up: back to the start of the phase
Back: pause
Menu: reset (press twice once it is running)
Vibration and beeps at each change can both be turned off in settings.

From the same developer, for apnea training: Apnea Tables - CO2 and O2 Hold Training. For other intervals: Round Timer and HIIT Timer.

Free to use, with no permissions asked.