When we bought our 5er, we noticed it really rocked a lot.
Internet search turned up the SteadyFast system. So, I purchased it, and after a bit installed it.
Results - GREAT, almost all the rocking is gone.
The quality of the components is first class, no cheap metal parts, just heavy duty steel with a good hard painted coating.
Directions are a bit complicated, but I just laid out all the parts, and figured out what went where BEFORE I started drilling.
This will require some elbow grease to drill about 15 holes in the frame, but other than that, it went well.
I own no interest in the company, just a satisfied customer.
I would recommend this if you have rocking and rolling on your trailer or fifth wheel.