At least two distinct case variants exist.  The nameplate on the one below identifies it as a model NHS 611-2471, made by New Haven.  The one above is shown as a model WS 611-4371 made (or sold) by the Westinghouse Electric Supply Co.  I  don't know what relationship existed between New Haven and Westinghouse, but these clocks are mechanically identical.  Both cases were made of mahogany, with lighter trim made of holly wood.

The actual "flip" action is created by the little metal fingers restraining the plates at the top, which bend them very slightly as the reel turns.  Once the edge of the plate passes the finger, the energy released by the plate regaining its normal shape causes it to flip.  Once flipped, gravity holds it down.  Whoever designed this mechanism must have been a card player.

The hours reel turns at 1/12 the speed of the minutes reel.  To give the two reels the same "flip action" (and the same appearance), each hour is repeated 5 times (5 x 12 = 60).  Or, in other words, the hour reel flips every 12 minutes, but the numbers repeat as needed.

The red and black disk seen in the above picture turns as the clock runs.  The mechanism is protected by a glass cylinder.

These are well made clocks, and the only problem I have seen with them is the tendency of the plates to stick together if the clock has not been run for a long period.