The Model 55 Compact was a submachine gun manufactured by American firearms company Police Ordnance Co.
The Model 55 was designed by Jack Purcell, one of the original members of the Police Ordnance Company. His Model 55 submachine gun was marketed as the "Compact SMG" and internally it was much the same as the Ingram Model 6, which the company manufactured. A few prototypes were made of the Model 55 and it was demonstrated to several Canadian and American police forces, but never adopted by any. It was very simple to manufacture, since the body consisted of a simple steel tube which the stock could retract in and out of. It was a mere 24 inches long, hence the "Compact" name. It is unlikely that any of these submachine guns still exist today.