i recently added a product called 'invisigrip' and it's much better. but to tell the truth i still like a good ruler. mine has sandpaper snippets (plain old very fine sandpaper and rubber cement from dh shop). make sure the ruler is at least 24" so you can fold your fabric 2X. with a ruler the acrylic is thicker and you can press down harder to keep things in place. the one with slits is too flexible and allows a little shifting even when the ruler is not moving and also some cutting or shaving into the plastic. it works better with thick arylic. at least i think so. that'll be 5 cents please (you can't buy anything for 2 cents any more). does anyone agree?