This is a timer with up to five intermediate alarms that vibrate but don't stop the timer; it looks like this when running:

The idea is there are 6 alarms -- one Main and 5 intermediate alarms. The main alarm is the total count down time; think of this as the regular time you'd set on a timer. At the end of this time period the phone gives off a small beep and vibrates twice. The intermediate alarms specify times when you want a notification, but don't want the timer to stop. For example, in a talk where the speaker is notified of having 15 minutes left, 10 minutes left, etc. The person timing wouldn't want to stare at the clock, but does want to promoptly notify the speaker of the remaining time. And of course wants to know when the entire time is up.

The source is hosted by google here:

To use it, press

Here is quite possibly the most boring youtube video ever showing this thing 'in action'.