The derby cover on your HD Dyna is pretty plain from the factory. Installing an after market Harley Dyna derby cover will add some customization to your American v-twin. An aftermarket derby cover will keep debris from getting into your clutch assembly as well as set your bike apart from the usual factory fare. RevZilla carries custom derby covers in black, chrome or machined styles so you can find the part that suits your style. There are even derby covers with transparent polycarbonate windows so you can view the inner workings of your spinning clutch pack