Available separatly or as part of a Wheel Kit. Use a Wheel Kit Axle Adaptor to attach an axle to your dock leg. Simply slide the long part with two bolts up over the dock leg, and slide the axle through the smaller part. Tighten all bolts to hold firmly in place. This bracket is designed to allow the dock leg to pass through to the ground if you prefer to keep the dock resting on its feet for the summer.