These are different than you will find elsewhere. They don't just have a sheet of flexible rubber tucked around them, they have a solid electroconductive rubber ring that snaps on to the edge for a perfect fit that doesn't come loose at inopportune moments. Use a little gel for a great suction seal. Release the pressure easily by pushing the button on the top, partially or completely. Customize the pressure by the number of squeezes on the suction gun handle. A great way to combine multiple sensations into one product!
Very easy to use, no adapters required. Just plug in a standard 2mm pin lead to hole in the rubber ring.