The two Longeron extention tubes are riveted to the bottom center of longerons with 5 ss rivets each. You need a good set of small clamps to hold the extention tube in place for drilling. a set of angle alumiun is used to support the battery across the gap and a second set of short aluminum angle is used to stop any lateral movment. A velcro strap is included to finish the rock solid hold on the batttery with this kit. I realy like the set up We shall see what it does to my W&B.