Just set the timer to the required length of session and choose music from the tab that you like to get you in the mood (or you can have silent) it will gong at the end of the session. It is great to use anywhere you have a laptop or access to a computer and bet of all it is free :-)
Sorry for those of you who dont have speakers at work, you had better speak to someone as taking a meditation break at your computer is more productive than going for a smoke break and healthier. Enjoy