I love a nice abacus, and think this one, with its rainbow colored beads, is especially lovely--and fairly unusual in having a handle, making it easy to calculate on the go! I have found a few other handled examples with a similar form, c. 1940s, which seems about right for this one. Beyond its calculating function, I find abacus' rewardingly useful for tracking of all sorts of things (i.e. move a bead to the left every time you make it to the gym!) Easy to hang from a nail or two on the wall. 

14 3/8" tall x 12" wide x 1"deep. There is a fair amount of wear to the finish on handle end of the frame and one red bead with a chip on one side, but overall good condition and looks great.