Are they swingarm spools or axle sliders? Well they are both really!! The spool is mounted to a special, black-anodized aluminum bracket (included with the kit). The product will give protection to the rear axle and swingarm area in a crash. When not protecting your investment the "cotton reel" can be used to lift the motorcycle using a rear stand with hooks. For rear wheel removal, you can take the Cotton Reels out of the aluminum blocks and insert them into the paddock stand bobbin screw holes. Designed for Aprilia RSV4-Factory / RSV4-R '09-'15 & Tuono V4 R (APRC) '11-'15.