If you have Board buddies this is a great accessory.  The track allows you to move the Buddies without remounting them on different areas of your fence.  It saves alot of time.  I attached a 1" x 3" x 3' piece of pine on the side of my fence and then mounted the track on top of that.  I didn't really see a way to mount the track directly on the fence.  I can't say enough about this product.  It is a must have.