Line Mate Junior Line Mate Jr. is designed to hold your mooring lines. This unique product is also ideal for keeping dockside power lines from hanging in the water-or for water hoses so they are out of the way, so no one can trip on them. A handy aid in docking on windy days, when docking can be a problem. Use your boat hook to grab onto the Line Mate Jr. and pull boat toward dock. The Line Mate Jr. is a heavy-duty casting made of Almag 35. A composition of Aluminum for corrosion resistance and Magnesium for strength.