This plate is used when a floating dock is connected into the side of another where there is no corner. This plate mounts to the side of the dock and the outer corners where the stringer ends needs to be reinforced with a corner iron if it does not already have a reinforced hinge plate. There could also be blocking and corner irons installed into the frame behind the T-hinge to strengthen the frame if needed. There is often a lot of torque in this location. The Stringers have been known to pull apart from the frame if not reinforced with steel plates and thru bolts.