The CAT-4 is similar to the CAT-3. The main aim of the CAT-4 is to provide a rewinder requiring no tension arm. The CAT-4 can be controlled by the printer through the external control input. More and more printers offer the required signal as a standard feature where before the addition of an expensive I/O board was necessary. Ideally, the printer should activate the rewinder only when printing or feeding forward.