The Onyx is a male masturbator which can receive signals from performers with either a Pearl or another Onyx device. It features a removable sleeve which can be replaced. The sleeve is made Fleshlight using the same synthetic skin material popularized in their main Fleshlight product.
The Pearl device is a dildo/vibrator which has sensors to recognize touch. Generally speaking this device will be more common for performers to own as the person with whom you are interacting must have an Onyx device to receive the signals.