Yes, they are held in place by the clamping force of the two plates and the blot in the center.
I have had it on the van for the last 2 years with many off raod adventures with no issues. I spent 10 days in Baja, 90% off raod. I have traveled from Gold Lake, CA to Dowineville, Ca off road on both fire raods and very rockey two tracks.
The only concern that I have for the "cargo" vas, would be the rear mount. It applys pressure to the lower foot of the mount. On my van, I am able to place it close to the window, were the wall of the van is strongest. I have a soultion, and that would be to modify the mount similar to the fornt, so that it has more surface area in contact with the wall of the van.
I have tried to get SMB to use these, but they were not interested. I am just going to offfer them up on the side. Another issue that SMB has with the Fiamma, is that they are using 3 mounts. The Fiamma is ment to be straight, and the van has a curve. This causes stress to the mount, pulling them loose or cracking.
I have had no issues with the PH top. It is close, and if you are on a slope, you need to compensate, as to not strike the FIamma.
Eli
Sano Fix??