Aluminum & Plastic Hub Guards Whistler Front Guard is PC Nylon Compound Whistler Pro / Rotator V4 Pro Guards (MUST BUY CONE SET TO USE ON V1 Whistler & V3 Rotator) Whistler Pro Upgrade / Rotator Pro Upgrade Cone Sets for previous versions (V1 Whistler / V3 Rotator DS) Bulimia V3 & Ghost V2 Hubs have Slider Compatible Guards Already Rear Guard, Ghost, and Phantom Guards are 14mm Threading to Replace Cones Bulimia Version Guard is 3/8″ Thread to Replace Cones All Hub Guards Are Sold Individually Aluminum & Plastic hub guard options that protect hub flanges. Thread onto axles, replacing hub cone nuts.