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.