The Dahle replacement cutting head is for use in the 556 / 558 series rolling (or rotary) trimmers.
The cutting head on the Professional series trimmers is easy to replace, simply remove the trim bar, and slide off the old head, and re-install the new head.
This part is for use in the following Dahle Professional paper trimmer: 556 and 558 models.
Dahle 556 (s) Professional RotaryTrimmer - 37 1/2"
Dahle 558 (s) Professional RotaryTrimmer - 51"