Mad Dart said

It is exactly how you describe it. When you shake it you can hear it Rattle just like a snake.........and no I aint bullshittin........haaaaaaa

In the instruction manual it says that this is the same technology that they use on airplanes and such... I think there are 9 roller counter weights in it.

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64physhy said

It's called the rattler because it has a pendulum (or maybe multiple pendulums) in it for balance instead of fluid. When you shut the engine off, you will hear a rattling or clunking sound from it as the pendulum winds down.

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