An acronym for Transcutaneous Electrical Nerve Stimulation, a TENS unit is an electrical device which delivers low-amperage electrical current to stimulate nerves, usually for pain relief. For certain types of back pain and RSI wrist pain, the TENS unit often produces better pain relief than drugs, making it popular with chiropractors, physical therapists, and sports medicine practitioners. The TENS unit has also been marketed as a fitness device under the theory that repeated electrical stimulation of muscle groups will work them in a manner similar to traditional exercise.
Many different varieties of TENS units exist, but most are smaller than a VHS cassette and run off of a nine volt battery or low-power AC adapter. Since the TENS unit can stimulate many parts of the body for many different reasons, a wide variety of attachments exist to deliver the current from the TENS unit to the skin. Typically though, the current is applied through the use of small electrode pads which are glued the the skin with a conductive adhesive. Once the current is flowing to the skin, the user can control the strength of the current and number of electrical pulses per minute.
Because of its ability to generate steady yet adjustable tingling sensations, the TENS unit has inevitably become a tool for exploring human sexual response. The device is generally capable of inducing orgasm in men as well as women, but it is used much more often by couples or groups as part of BDSM play than for solo masturbation. By grabbing the knobs, the top is able to precisely control the sensations felt by the bottom, which is a common theme in BDSM and power exchange play. The top is also taking responsibility for the safety of the bottom, since the current from the TENS unit is potentially hazardous. At US$200 to US$300, the device is an excellent investment for electrosexual stimulation, since it provides intense feelings without leaving permanent marks, and serves as a power source for countless attachments that will open many avenues for exploration.