Soldered along the edge of the solder side. This is most likely the model number.
overall: 5 1/2 in x 2 1/2 in x 1/2 in
This record contains one flip flop B201E. It has one blue handle on the top and one connector on the bottom. The manufacturer name and "Maynard, Massachusetts" are in raised lettering on the back of the handle. The title of the object is soldered along the edge of the solder side.