Clitoral suction toys can be a bit of a mystery if you’re unfamiliar with their ins and outs. Vibrators contain motors that provide the vibration by just stimulating via shaking, but a suction toy is a little more complex.
They work by modulating air pressure with an internal diaphragm. They all have a mouth, and inside that mouth is a (typically) silicone membrane that an internal motor moves in and out. When you press the mouth against your body, it traps the air in there, keeping it from escaping. The movement of the membrane uses that air to create modulating high and low air pressure. Those changes in air pressure create the sucking sensation suction toys are famous for.
When Womanizer first launched this concept, it called this innovation “Pleasure Air Technology.” Although that technology still remains, other suction toys have come up with their own version that is just as good, if not better, depending on your preference.