I got them for a popup and then hybrid we used to own. It's amazing how much of a difference they can make both during the summer to keep the heat out, and winter to keep the heat in.
You can make your own for less using some space blankets if you have more skill and time than money.
Attaching them to a hybrid can be interesting, because you need to find a way to keep the top secured in place. On our hybrid, the tent material was attached to the inside wall, so the area inside the opening was a good place to put the velcro. I requested the velcro pre-sewn into the top of the ones I ordered. The shock cord was just stretched under the bed/door. Here's a link to a post of what I did: Attaching Popup Gizmos to a HTT
I believe it might be better to face the shiny side toward the heat (e.g, reflect it back toward the sun during the summer, and dark side up to absorb heat during the winter), but Bob at PUG swears it doesn't matter. He says, "shiny side up always."