Correct... It's a vibrating insert that gets installed under the upholstery of the seat. It revs faster and slower, in conjunction with the RPMs of the engine.
The ironic part is: Why would you want (or need for that matter) to add MORE vibration to a Harley???
They don't call then "Milwaukee Vibrators" for nuthin.......
And if you're gonna advertize a vibrating seat for an RC51, at least put a passenger seat on it.......