A bridge plate mounts between the bridge bars in your truck's rear air suspension. These give you a place to mount your bags to and also further reinforce the bridge bars, plus they are in a Maltese Cross shape cut out for some extra flair! Four holes are cut out for you to run your air line to the bag fitting and install the bag mounting bolts/hardware. The plates we sell are solid steel and offer more than enough strength to mount your bags to!