There used to be a very informative website called vintagecardboard.com that covered all things Obaks. Unfortunately, it no longer exists, but I was able to run a web archive search and come up with vintagecardboard's listings of which 1910 Obaks came with which backs. The link takes a couple seconds to load, so don't be deterred by the wayback machine beta page that initially shows up.
http://web.archive.org/web/200811211.../ref_obkbk.htm