Durable, heavy duty suction cup. Portable stern light is ideal for ski boats, sailboats and any boaters who do not want an attachment method that might mar the surface. Requires (2) “D” cell batteries. Designed for speeds up to 7 knots. For nighttime operation of small boats and tenders w/o 12V systems. Not intended to meet U.S.C.G. regulations. Not for use on boats that can exceed seven knots.