noob question about thumbnail sizes! (1 Viewer)

[mpnoob]

Hi all, brand new MP user! I want to put custom thumbnails in for all of my directories, but what I want to know is how they are supposed to be named in relation to the directory, and also the size in pixels for a 1:1 display of the pic for the 'Big Icon' size?

I guessed 215 x 310

Thanks in advance