“Neno plug” refers to:
Option 3 ( A Small Hearing Aid ) is the right answer.
Nanoplug developed the world’s first 100% invisible, affordable, instant fit, user programmable hearing aid that helps a younger, hipper audience with hearing loss to solve their problem with embarrassment and social stigma using the latest nanotechnologies.
An instant-charging nanobattery makes this hearing aid smaller than a coffee bean. The Nanoplug is the most radical thing to happen to hearing loss since the invention of the aid itself.