This mod is in reply to a request in the Nexus forums for a magic item that allows the user to become invisible, but only whilst sneaking.

                                  

Whilst wearing the ring AND sneaking the wearer becomes subject to a 75% chameleon effect.

Because this ring is quite a powerful item you're going to have to work to get it! Look outside the bookshop in the Imperial City for a clue as to the ring's whereabouts.