They change tint with available sunlight so you can ride in all light conditions with the one pair of glasses.
Barz Optics photochromic glasses have a slight 15% tint in low light. As the sun and UV intensifies they tint to category 3 which is about a 75% tint of normal sunglasses.
Kevin says the photochromic effect works with an open-face helmet, but may not work in full-face helmets if the visor is UV treated. However, the tint will darken if you raise the visor.
I find they change to a suitable tint in about 4-5 seconds and full tint in about 10 seconds. Similarly, if you ride into a tunnel they change fast enough to adjust to the changed light conditions.
All in one
Kevin says they are also working on combining all these features – photochromic, polarised and bifocal – into one set of sunglasses.
“As nobody has produced such a lens previously the cost of the initial set up is extremely high and to offset this we have decided to crowd fund 30% of the initial costs on crowdfunding web site indiegogo.com,” Kavein says.
“We also figure that by going the crowdfunding route it will give the glasses great exposure.
“We have decided to offer around 40% off the retail price to anyone who supports us on Indiegogo.”