150mm vacuum pump cup, with swivel and double ball tilt top. A bit of a mouthful, but basically a very strong vacuum mount with multiple joints to allow easy camera positioning in almost any angle, inside and out. The camera mount is held in place on a smooth, clean angle (ideally flat or very shallow angle) by a vacuum. This is created by you pumping a button on the base quickly until you see the red line on the button disappear. At this point the cup is rated as supporting up to 2kg in weight. When the red line re-appears you need to start pumping again!