help desk - timers

So all the anti-procrastination behavior-mod types keep telling me to get a timer that beeps every five minutes, so I can find out, every five minutes, whether or not I am on task.

Here’s another technique that works pretty well to keep me on task: Sometimes I use a timer that beeps every five minutes. And when the timer beeps, I mark on a graph, whether I was on task or off task at the time of the beep. That’s a great one for cutting down on my daydreaming. It gives me a rule that specifies a more immediate deadline. Stay on task, because that timer is going to beep pretty soon, and you don’t want to ruin your graph. So instead of having a daily deadline, or an hourly deadline, I’ve got a sort of five-minute deadline, except I’m never too sure how soon it’s going to be.
I'll Stop Procrastinating When I Get Around to It
by Dick Malott
Chapter 3: How to Get Yourself to Write

So here's my question.

Where does one buy an every-five-minute timer?

Behaviorists toss off this advice like the rest of us just know that:

a) every-five-minute timers exist

and

b) where we go to get one

Well, I don't know.

When I first heard tell of folks setting 5-minute timers to find out whether they were on task, I didn't want to know whether or not I was on task every 5-minutes.

But now I do want to know, but I don't have a timer and I don't know where to get one.

Thank you in advance.

[pause]

The word interval has just popped into my head.

interval as in interval timer

There must be such an animal.

[pause]

Is this it?

They seem to have quite a few of these things for boxers. Apparently boxing is easier than writing. They only have 2 to 3 minute intervals.

Or maybe that means boxing is harder.