It’s only charts. Use them on whatever you want (pillow, sweater, sleeping bags…).

Those designs are from xkcd comic (http://www.xkcd.com). You can see the full comic here : http://xkcd.com/674/ (read the others they’re great too).
As the comic is published under a Creative Commons Attribution-NonCommercial 2.5 License, you can use these charts for any purpose as long as it’s not a commercial one.