The Plastic "T" (made from cutting board) bolts down to/thru the floor. This keeps the seat box attached to the boat. Slide bolts hold the box in position, forward/aft side to side. A wood tray/cap goes over the "T", so it does not get in the way of gear storage. Or, if there is a drawer, the drawer will glide over the it. This system workes really well and is very simple to build.