Or from Latin baculum a stick, because the squire would practice with a staff, not a sword. Meaning evolved from knight in training to young unmarried man (early 14c.). Bachelor party as a pre-wedding ritual is from 1882.
A transcutaneous electrical nerve stimulation (TENS) unit is a device that sends small electrical currents to targeted body parts. These currents are used to relieve pain. Some TENS units are designed for use in a hospital or healthcare facility.
The working of the TENS is simple in which electrodes are placed on the affected part and amplitude of the stimulation is controlled by adjusting different settings of voltage, pulse width, and current. The electrodes send electric current in the body through the electrodes and stimulate nerve pathways results in a reduced perception of pain.