Hey, sorry I didn't see this!
They're intended to be printed on Letter size paper, but I personally fly a little fast and loose with concepts like "appropriate sizes" and "recognized standards", so ¯\_(ツ)_/¯
I honestly made this so long ago that I'm not sure if I still have the project to remove the background from! I'll take a look and if I find anything, I'll try to post an update.