There are 3 different types of cutting head assembly that fit different versions of the Dahle 508 trimmer.
Replacement of the blade for the 508 trimmer is achieved by replcing the cutting head assembly.
The cutting head contains the rotary blade in a self contained unit that also contains the rubber traction wheel.
The best way to identify the correct blade / cutting head assembly for the 508 is via the article number - usually on a lable on the underside of the 508 trimmer.
If there is no article number, another method is to look at the shape of the guide bar (round or rectangular) combined with the colour of the existing head assembly (Grey or Black).
The 3 different cutting heads for the Dahle 508 are listed below:
