Here is an interval timer made for boxing and other similar sports. JAB puts you in full control of the rounds, so you can adjust its prepare, warning, intense, and rest settings. Its Intense feature lets you divide a round into equal segments to push your body the right way.
JAB comes with sound and light signals. It lets you listen to Apple Music or Spotify without leaving the app. JAB plays well with Siri too. It works in both display orientations.[where to get it]