If we ignore large trucks and specialist vehicles we probably need

Slant Back Tonneau Cover?

If we ignore large trucks and specialist vehicles we probably need … Does anybody know what I’m talking about?
I’ve seen different versions as well. I just want something light and easy so I can throw it up in case it starts raining or snowing and I don’t want the dogs or my cargo to get soaked.
They shouldn’t be all that expensive, there isn’t much to them. Except I have a K15 not a K5.