I usually use MP320 as mobile mp3 player.
Its battery lasts longer than smartphone,
and compact.

Though MP320 is fairly old product,
I still use this because I love speed change function of this!

But today
It freezed suddenly,
All buttons stopped responding!

There is reset button but I could not use this without a sharp object such as sharp pencil.

There isn’t power off button in this player,
I have to wait until the battery will run out.

I hope all devices have a power off button which physically cuts electricity.