These are PKT's kid kart brake rotor hubs. They are available for 25mm, 30mm & 1-1/4" axles. 25mm & 30mm have 6mm key slots while the 1-1/4" hub has a 1/4" key slot. The hubs come with all hardware and are finished in black anodize with laser engraving. The hubs also fit the Noonan brake rotor. Sold individually.