My van has a 6" curb in the driveway and they are perfect for supporting it through the curb. I have a 32ft RV and the first few times I used them they worked great. They didn't even move when they got her. I had read that people complained about the smell when opened indoors, so I opened mine on the porch and left them out overnight. Now they are in the garage, I didn't notice any smell. I've tried finding something similar at local camping stores - to no avail. I'm so glad I found her at Revain! I will say - I thought they were solid based on the photos but they are not. There's plastic underneath, like most other curb ramps, but they're still heavy.