Iphone or Android Chess Clocks

I recently downloaded an app onto my smartphone that turns the phone into a chess clock.  Very simple interface, two facing clocks.  When you hit one side the clock on the other begins counting down.  It adds increments, tracks move numbers.  Simply great.

What I am wondering is if such a device would be tournament legal? Does anyone currently use these?

Anybody else use these programs.  Can anybody suggest one they feel is better than others?  Thoughts?

The one I am using is called "Chess Clock for Android"

A tablet or  phone should be fun to use.   The best simple chess clock for Android  is  Chess Cloid by Fireworks.  The best simple chess clock for Iphone/Ipad  is  Game Timer by Thana!    They are free!  I hope you find them very useful!

For Iphone, try 'Othman's Chess Clock'. It's simple and very easy to use.