Kung fu Stretching Timer FREE (my.abcdefinder.sterchingtimer) on Google Play
This app is a "Kung fu Stretching Timer" it makes doing proper time stretches a ease no more look up at the clock just pick a option of 30sec,45sec,60sec,90sec,120sec,180sec and push start button and it will alert you with a notification sound when time has expired.And best of all it's Free