Roger, the mirka pads are hook and loop, and they have a foam built into them for going over contours. These are used wet. I think they are called abralon? pads. I didn't know they were available in 4000, 2000 was the finest grit available when I was using them. I've been using 3M 3000 lately.
Found them on the web for ya-abralon
Oh, and another very important thing to remember when using any of these DA systems- make absolutely sure your DA, hose ends, and hose is perfectly clean before use, small particles of abrasive or dirt from using these items in regular body work will ruin your day if they fall from the tool or hose and land on the hood and get ground into the fresh paint. One tiny piece of anything. Most people that sand and buff for a living have a dedicated DA for colorsanding.