Cheers AerocatS2A, but the beauty of chinagraph is that you can just scribble ATIS/ clearances on your kneepad and then rub it off and change as required in flight. I've used non-permanent markers before, but they leave bigger marks on fingers/cuffs than chinagraphs.
and the beauty of mechanical chinagraph over your normal one is that they won't leave marks on anything you don't want + you can see if the lead is broken.
Not a biggie for all you bigger cockpit dwellers where you use notepads and pens, but for little whirly things with doors off, i like my kneepads compact and preferably covered with plastic / glass.