Wires on the visor provide a fog free view via a heated film inside the visor

SebastianVettel wearing an Arai helmet was seen in the wet Jerez tests with this heated Visor.  Not new to F1, as Schuberth Helmet wearers raced a similar solution a few years ago.  The wires leading into the visor, pass a current to a heated film inside the visor to prevent fogging in the cold and wet conditions.

Quote from my 2008 Monaco GP technical review on Autosport.com

“One feature not seen in a race before was a novel anti-fog visor used by the Schuberth-helmeted drivers (including the Ferrari drivers and Nico Rosberg). We have seen drivers struggling to stop the inside of the visor from misting during previous wet races, as the hot breath from the drivers’ exertion condenses on the cold visor.

Some drivers prop open the visor a little to let air pass inside, or use a double-glazing like inner visor. Schuberth’s solution was to place an electric element inside the visor, to heat the visor slightly.

Much like the demisting element in car windscreen, this prevents the breath forming a mist inside the visor. At the moment the visor is an add-on to the standard RF1 helmet, so the electric cable feeding the element runs exposed down the side of the driver’s element to connect via a plug into the car’s electrical loom.”

http://www.autosport.com/journal/article.php/id/1592

Schuberth heated visor Monaco 2008