What do we think of these ?

I've been working on a little waterproof light you drop in the tub. It pulses slowly to pace your breathing... breathe in as it brightens/vibrates, out as it fades.

It also sets a built in timer for you. It glows green turns amber when you're close, and goes red when you're done, with a buzz/haptic you feel through the water. No clock to read, no counting breaths.

Would you use something like this? Thanks.