Serengeti Polar PhD

“Lighter, stronger, better” is the theme of Serengeti’s new Polar PhD technology, a clear lens material said to be the same stuff used for fighter jet cockpits and skyscraper windows. The photochromic, polarized lens, touted as lighter than glass and polycarbonate, is the staple material for about a dozen of the company’s newest sunglasses.

The mystery material is a polyurethane polymer called NXT, made by a Pittsburgh, Penn., company. It is used in other sunglass lenses and not unique to Serengeti.

But unlike other companies that employ NXT, it’s not the durability that Serengeti claims sets its technology apart. The polarizing layer in the lens is bonded to the back of the lens surface. That process, Serengeti says, makes its lenses provide “98 percent polarizing efficiency.” That’s a good thing as some lenses — though not most dark-tinted sports lenses — have much lower efficiency ratings, Serengeti cites. Another advantage to the bonding: it eliminates the chance of delamination.

As noted, all the lenses are photochromic, meaning they automatically change tint according to lighting conditions. As is industry standard, they block 100 percent of UVA and UVB rays.

The Polar PhD lenses are available on 11 Serengti sunglasses, starting at about $160. www.serengeti-eyewear.com

—Ryan Dionne