Yes, I am aware of the ones at the hardware store.
I have a few questions.
Is the one you reference smaller than 0.9 inches on every side?
Does it only take 2 mA to run?
And does it provide an easy to read output such as RS232, pulse width,
or analog voltage?

These are inportant things when you are building a small robot,
or a battery based system that will run all the time,
or want to use the output on a microcontroller.

Bob