Well, that didn't take long. In less than a year, electrochromic sunglasses have gone from being experimental to an actual product, with Dutch startup Ctrl announcing its tint-on-demand Ctrl One cycling glasses just this month. Should you prefer multi-use electronically-tinting sunglasses, however, you might want to get yourself a pair of Skugga shades.

Electrochromic sunglasses are similar to traditional photochromic transition eyeglasses, in that their lenses automatically switch from clear to tinted when exposed to ultraviolet light. That said, while photochromic lenses take several seconds to make the change, electrochromic lenses do so instantly. Additionally, their users can switch between clear and tinted modes manually – this could be particularly useful in situations such as driving, in which photochromic lenses won't darken because they're shaded from the sunlight.

While Ctrl utilizes "e-tint" technology developed by Ohio-based company AlphaMicron, Skugga has gone with a system from Sweden's LC-Tec. It incorporates liquid crystal filters within the lenses, that darken or brighten in response to the application of a low-voltage electrical current.

As with the Ctrl Ones, users can either allow the glasses to switch on their own in response to changing lighting conditions (thanks to an ambient light sensor), or they can switch them themselves. In the case of the Skuggas, it's also possible to fine-tune the degree of tint utilizing a smartphone app.

According to the designers, the lenses block 100 percent of UVA and UVB light even at their lightest tint – they do not go completely untinted. Additionally, for people who care to keep track of such things, the app lets users know their own level of UV exposure over time. For users who don't want to be constantly accessing the app, the glasses can be switched between auto and two user-defined tint presets by flipping their right-hand arm.

The glasses' battery is charged wirelessly, with one charge reportedly being good for about 8 hours in auto or 12 in manual. The lenses automatically default to their lightest tint when the battery is dead.

Stockholm-based Skugga Eyewear is currently raising production funds for its sunglasses, on Kickstarter. A pledge of 2,049 krona (about US$240) is required to get a pair, when and if they're ready to go.

More information is available in the pitch video below.

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