i have the one with the 1/2" slots on it. it comes in two sizes. one has like, 12 slots or something, the other has like 6 slots. you get the idea. i got it from joann's. the big one was supposed to cost around $24.oo and the small one around $18.00, but the dumb manager mixed them up even after i said he must be making a mistake. the people behind me said "take it!".so i did. i'm not crazy about it. it slips like mad and even though you're supposed to be able to press down on one end so the slits rest off the end of the fabric and hang up there, i find it doesn't work as well as a good ruler with tacky stuff on the bottom.
my joann's is the fabric store from hell!