I had ordered a Surflex slipper clutch for my '05 SM510R from FBF through my local Husky dealer. When the clutch arrived there wasn't any documentation or parts numbers for replacement parts. When I called FBF for spares they didn't have any information. So I emailed Surflex in Italy and told them i'd really like to have spares and some documentation. In response, Surflex is mailing me a replacement set of springs, steel and friction disks for my slipper clutch for free! They also emailed me directions for installation as well as a copy of their brochure and a photo of my free stuff.