Such a smart little box! The lid--locked tightly when closed--is comprised of two parts, opening through a series of moves, via which the interior compartment is revealed. I've found a few other boxes designed in a similar manner, mostly dating from the late 19th and early 20th century--most commonly vesta, which held matches, and also often including a hidden match striker on the flat of the lower section of the lid. The interior compartment on this one seems a bit small for that, making me think maybe a snuff box instead, though I'm not sure why the two small holes at bottom (which just barely go all the way through, so not much other than sand would fall through.) In any case, really a lovely little piece, perfect for putting in a pocket or a suitcase for securely storing a small stash. 

4 1/2" long x 1 5/8" tall x 1" deep. Great condition, with a nice warm patina.