I have a similar pad for my ROS, complete with the hole pattern to suck up sawdust. Its about 5/8" thick soft foam, with velcro on both sides - loops on one side to attach to the ROS, and hooks on the other side to attach the sandpaper.

It conforms nicely to concave surfaces, but I didn't find it very useful for the kayak. I think the foam was too soft, and the sandpaper didn't get any "bite". It would have taken forever. I switched back to a combination of curved scraper, ROS without the foam, & hand sanding. If I stumble across a similar product with a stiffer foam, I might give it another try.