I came across these guys when I was at Williams-Sonoma recently. I'm terrible at guessing the thickness when rolling out dough. I want to kiss the person who came up with these; what a great idea. Now, all I need to do is strap the correct band size on my rolling pin and viola! No more guesstimating dough thickness.
I haven't had a chance to use them myself, but my sister used them for her sugar cookies and said it worked pretty well. You just have to make sure the dough is between the two bands. Lucky for me I have a long rolling pin.
I guess I need to make a pie so I can test them out.