I've searched but have not found another button like this one, so am not sure what habit it wants us to get, but I rather love the mystery of it! Perhaps the enlarged E and B hold a clue, but I haven't figured it out. I did find an old Sante Fe railroad pin that says "Get the Safety Habit," so possibly it has a railroad connection. Anyway, a pretty great button, and definitely a very old one!
Spotting to the cream ground and a little rusting around the rim on the back. 1" diameter.