Also, while it is true that they help considerably with movement and bounce, don't expect them to eliminate it completely. They won't.
I don't know how they could not. They are bolted directly to the frame, so your RV frame is literally sitting on jacks when they are down.
I mean, it's not absolutely 100% rock-solid, sure you can feel a vibration across the house, but it's an absolute night-and-day difference jacks down vs. jacks up.
Maybe the blinds wiggle a tiny bit when I roll over in bed when they are down. As opposed to every blind in the RV going SLAP SLAP SLAP when I roll over when the jacks are up.