I finally got my package of cling vinyl today and discovered that it is indeed the stuff the vinyl open-reel tape retention strips were made of in the days of yore. The stuff is Grafix-brand "Cling Vinyl", KFC9-ASST. 9 9"x12" paper-backed sheets. Easy enough to cut with scissors or standard paper cutter. 6" long x 3/8" wide seems to be about right. No more foam blocks! --Chuck