This is a clockface which shows the current swatch internet time for Fitbit OS.
To build this app yourself, you have to own a Fitbit Ionic and visit this website: https://studio.fitbit.com/
To download the clockface directly follow this link on your smartphone: https://gam.fitbit.com/gallery/clock/c585da0a-d97c-406c-9b0d-0682b9f726db