Are they cotton reels or spindle sliders Well they are both really!!The Cotton Reel protects the swingarm and swingarm core components in the event of a crash or drop, but also double up as paddock stand bobbins. Allowing the motorcycles rear wheel to be lifted into the air via a paddock stand to performance chain adjustment, tyre changes and cleaning!This particular pair of R&G Cotton Reels are compatible with the Kawasaki Z900 17, Z900RS 21-, ZH2 20- and Triumph Bonneville Bobber 17-20 modelsPlease check your swingarm for threaded lugs to accommodate these cotton reels. Certain markets for 2017 do not have these lugs.