Used to upgrade from the stock caliper to a single 108mm radial caliper on the rear of your Touring bike. Looks great and will compliment any bike's style. Allows fitment of 108mm style aftermarket radial calipers and will allow up to a 300mm rotor size. - For standard 25mm axle diameter - For most 108mm radial aftermarket calipers - Up to 300mm brake rotor - Black anodized CNC machined billet aluminum. Note: Caliper spacers may be required to space off your caliper to the appropriate height, depending on your rotor size.