Fitting the shredder blade
The manual Page 23 of 52
Note on new machines that come standard with a mowing head only: In addition to the "shredder blade mounting kit", a "shredder blade retrofit kit" is required to mount a shredder blade. Kits are available from your servicing dealer.
1, The dealers don't know what the two kits are and Stihl's technical support don't know either.
However talking it over with Gavin from technical support