Global Motorsport Media
At least two F1 drivers are still refusing to update their helmets with the new feature designed in the wake of Felipe Massa's 2009 head injury.
Last month at Suzuka, it was believed all the race drivers were wearing helmets fitted with a bulletproof Zylon strip across the top of their visors.
But because the strips add 50 grams of weight to the helmet, and affect the visor tint coatings and also the tear-off strips, it ultimately emerged that some drivers remained unwilling.
Indeed, Turun Sanomat reports that the zylon visor is not yet mandatory, despite most drivers now using it because it is safer.
"(Michael) Schumacher and (Lewis) Hamilton don't use it because it saves them an extra 50 grams," said Japanese helmet manufacturer Arai's Peter Burger.
"Perhaps with the g-forces it adds up to a bit more (than 50 grams)," he conceded.
He said world champion Sebastian Vettel, on the other hand, does use the zylon strip.
Perhaps with the g-forces it adds up to a bit more than 50 grams
"I had to carefully explain to him why to use something that is not actually compulsory," said Burger.
"It was supposed to become mandatory in Japan but the FIA only sent a letter to each driver strongly recommending that they use it.