I have to agree on the dura-block. I bought a set yesterday and they are the BEST I have used. I have many 3M pads soft and hard but they really dont work that great for blocking guidecoat.
I think the dura block site would be better served to add better photographs to the site. Some are really hard to tell. Dont click on the large kit for a picture
Also be nice if they had a block with a large radius on just one side for sanding up to fender lips.