I bought a set from Sears around '80. At the time they did what I needed. I was always wary of using them. Most times I ended up jacking one wheel up at a time and placing the ramps under rather than driving onto. I would back off them though.
I don't like the short area for the tire to stop, the potential for the ramps to slide when driving on, the size of the strut supports, and the fact they didn't weld the bottom area along that 90° fold.
Lol, other than that, they've been just fine!