Fangs plug / Safe plug

Fang plug is inspired by the serpent's teeth. The snake's fangs are often encased by a layer of soft membrane. When the snake attacks preys, the soft film will retreat into the palate. The dangerous metal plug is wrapped by insulative plastic shell. When the plug is plugging-into the jack, the insulative shell would retract because of the spring. As a result, the users’ fingers would not touch the metal plug directly at all. The same is true for pulling out the plug. The insulative shell would pop up due to the spring, which would avoid the dangers caused by exposed metal inserts for the plug is not plugged-in tightly.