Powder coated aluminum “TOP MOUNT”. This can be attached to any horizontal surface. Concrete, wood, RV tongue. Attaching hardware is not included. Don’t forget the Reducer Sleeve for Mounts if your pole is the 15′ (2.5″ base). The holes in the base are 7/16″ in diameter, and the centers of the holes are 6 7/8″ apart side to side and top to bottom.