- You may be looking for a Leviathan control collar.
The restraint collar was a device used by the Nebari to keep their prisoners under control. The collar could be used to inflict pain upon the victim using a control device that was placed on or possibly embedded in the captor's forehead.
At least two designs have been seen in use, a blue design that fits around the back of the neck and is open in the front and a larger gold design that completely encompasses the neck. The collars have been manufactured in multiple sizes to fit different species, such as Pilots. This larger design is also known to be programmable, able to automatically inject the captive with a lethal dose of toxin should the collar detect certain conditions that suggest attempted escape or control by the captive.