In the center of the tripods adjustable center column is a 3/8″ thread bolt that accepts most major brands of ball or pan head mounts. If you remove the hook from the bottom of the center column you will also find another 3/8″ mount there. This can be a quick way of hanging your camera from the bottom of the tripod for that close up macro, if you don’t want to pull the center column and reverse it. There is also a bubble level incorporated into the Top of the legs. I would pretty much ignore that. It is not accurate in the slightest, and I am not the first to make this statement. Just pick your self up a level to mount on the hot shoe, or carry a small level and level the ball head.