Many installs require the load coil on your predator antenna to be much higher. We find that Freightliner Cascadia, and Kenworth T660 and Kenworth T680 trucks - to name a few, require a much longer shaft. If you already have a 9 or 12" shaft on your predator and move into one of these trucks, or decide that you want to extend your load coil placement for any reason, this shaft will work with any Predator Antenna.