I've been trying to remember what this opaque plastic strip is called!?

I've been trying to remember the name of this thing and its driving me crazy, like its on the tip of my tongue. It's a kind of transparent/opaque plastic strip that has a smooth side and a rigged/bumpy side on the other. At the end of it there is a small 'box' that you put the strip in a pull through to tighten it. If you know what this is called, even if it's just a wild guess, please help me out ><