Control bracelet
A control bracelet was a device worn upon the wrist of Eymorg inhabitants of Sigma Draconis VI. It had several functions such as the ability to control the operation of a pain band and to render an individual unconscious. It was so powerful that it could render the entire crew of a ship unconscious. The Eymorg leader  used this device to render the entire crew of the  unconscious when she sought to steal Commander Spock's brain. ()
Technology