overall: 1 3/8 in x 20 1/2 in x 1 3/8 in; platten surface: 15 3/8 in
The assembly consists of a black plastic platten on a steel shaft with a ratchet detent on one end. The square shaft at the other end is spring loaded. A separate metal collar fits over platten end with the square shaft. The ratchet detent is stamped with 54 which seems to be the number of teeth. No other markings found.