Found these at the local flea market last weekend and knew you would love them for your scrapbooking and altered books. Perhaps they are the keys to someones heart? They are 3" long and come in a set of 2 on a ring. The brass discs have a letter and a number stamped on them. They have an engraved "No" which makes us believe the letter and number were stamped after the rooms were assigned numbers.  Whatever the situation you will have fun with these! They sold individually and there are 5 sets.