The 6″ cube is the base product that comes with 1 ribbed and reinforced peg. The cube has 4 peg holes in each of the top corners and a cutout on the sides. Two cutouts are 3/4″ deep and the other two cutouts are 1.5″ deep. There are several attachment options available to add to the cube to make it more versatile. Each attachment can be connected with the included 3″x 3/8″- 16 threaded hex head bolt. The attachment options are windows, hooks, slick chucks, jugged rails, plugs, slopers, or extra pegs.