TKI CNC Billet ilder wheels made of 6061 Aircraft gade aluminum then hard anodized black for a durable finish. The highest quality NTN 6205 sealed bearings are included for the ultimate ride. Biller wheels offer less rolling resistance for more top speed and are tougher than any plastic wheel there is. You can install 8"or 9" TKI CNC wheels on the outside of our 4 wheel axle kits with the Avid wheels on the inside to save costs and still have billet look. Note: YOU MUST ORDER THE CORRECT TKI CNC OFFSET AXLE FOR THESE WHEELS TO PROPERLY FIT. ORDER 1" OFFEST FOR 10" , AND 1/2" OFFSET FOR 8" OR 9" . WHEELS ARE SOLD EACH .