This grip tape works VERY well... It's the best I have found... Your ruler will not slip with this on the back of it... I have tried Invisigrip, the sheets of liner that cover the backs of entire rulers, and the little rubbery grippy nubs, and they don't work near as well as this....
Matter of fact, if you're working on a quilt with embroidery or applique on it, I'd recommend turning the ruler over and using the smooth side because this will snag the embroidery thread that is used... It doesn't snag your fabric, though it could possibly snag flannel or fleece if you have that in a quilt top, so I would flip the ruler over to the smooth side for those kinds of fabrics, too.