The Super Knuckle Suction Cup Adapter allows you to mount the system to hard, flat non-porous surfaces such as ceramic tile, glass and stone without damaging the surface. It consists of a 3" suction cup on one side and a ball joint on the other. The suction cup has a red indicator line on the white pump button. When maximum vacuum is achieved the red line stays hidden. Ideal for temporarily mounting lightweight video cameras or a variety of lights and sound recording equipment.