Thin cheap plastic. Definitely NOT worth the money! If you must have a brand you will be sooooo disappointed! CAMCO wheel chocks are much cheaper and better quality!
Lightweight plastic. what is good. but that doesn't stop the trailer from rolling. Maybe a rubber or grippy edge will keep everything in place. I use it with a trailer jack chock. So it looks like it will do the job in combination.
Hollow plastic? I wanted hard rubber and I thought they would. I haven't read the details. As for the product, it will be fine for a light trailer, but not for accommodating a camper van in my class.
It could hold an average 10 speed bike in place. Don't expect it to carry a reasonably sized pendant with any amount of print. It's a thin piece of vinyl shit. I went to Northern Hydraulics and bought a set of heavy duty rubber pads for less money. This is an absolute rip off for the price and intended use. I return it; I'm surprised Revane sold something so useless for such a high price.