Sultry Sub is an additional receiver for Mystim Cluster Buster to control Mystim Electrosex toys and other e-stim gadgets.The two contact buttons of Mystim's self-adhesive bipolar electrode can be pressed into the two recesses on the bottom side so that the Sultry Sub sits directly on your body. If you already own other electrosex toys, you can connect them to the receiver using the included cable, allowing Cluster Buster to control them wirelessly as well.Charging Sultry Sub is simply done using a standard micro-USB cable.Please make sure you order the receiver with the your preferred frequency.Product details:✓ receiver module for Mystim Cluster Buster✓ charge via USB cable✓ Frequency range: 5 - 70 Hz✓ Intensity: 0 - 70 mA