Differentiating Between 1x and 2x

How would I know whether my files are 1x or 2x? As a matter of fact, what do they mean? I want to know what my files are so I know which released files are safe to download, seeing as 1x and 2x could crash...

1x refers to normal resolution, ie the dimensions of the default files (face files are 256x256). 2x files are double resolution patches (eg 512x512 face files). I don't have a listing of all the default (1x) file dimensions handy as I hardly do any work with art files so perhaps someone else can fill you in on the specifics for the other files.