This is what I do with every one of my rulers. I go to JoAnns and buy some of their clear vinyal (sp) that you buy to cover tablecloths or whatever. They sell in by the yard but you only need about 4 inches since the tubes are so long. Cut narrow stips to lay on the back side of each ruler...up, down, across the top and bottom. Ruler NEVER slides and sooo cheap!
Julie in NM