Interesting enough, the black opaque plastic used for the Flak 2.0XL is transparent under infrared light.
Just a quick video showing Ultraviolet/UV light being blocked by Oakley Prizm Trail, Low Light, Deep Water Polarized, Tungsten Polarized, and Snow Sapphire.
As a recap, Ultraviolet light can be dangerous for our eyes and skin and covers the range below 400nm (Visible light for the human eye typically ranges between 380nm to 700nm).
- UV-A 315nm to 400nm - The most commonly occurring wavelength of UV Radiation reaching the earth from the Sun (around 90% of the UV that reaches the earth)
- UV-B 280nm to 315nm - Mostly filtered by the atmosphere, responsible for a lot of delayed tanning/burning of skin, can't get past skin
- UV-C 100nm to 280nm - The most damaging wavelength of UV, often used for viral/bacterial sterilization, filtered completely by our atmosphere so can only occur artificially on earth.
Infrared is in the range above 700nm, various heat sources also give off infrared light but because modified cameras like mine can only natively see up to around 1200nm, it won't have "heat vision" which would be up in the range of 7,000nm+. My specific modification on my camera allows me to see around the range of 290nm to around 1200nm.
Any light source within the 100~1200+ range can damage your vision if the intensity is high enough. In other words don't stare into the sun even though you have sunglasses on, especially since these lenses (and most others) do not block infrared light at all, and the sun is an excellent intense source of infrared light. I actually have a special set of Neutral Density filters for my camera that blocks even infrared light for the purpose of photographing a solar eclipse without frying my sensor, infrared blocking isn't that common except for internal applications (Such as the 'hot filter' that blocks UV and IR, that was originally installed above camera sensors before conversion to a full spectrum one).
VLT (Visible Light Transmission) only applies to light between the 380nm to 700nm range (and Oakley lens blocks 400nm and below). So one of these lens that has 15% VLT is still 0% UV, and possibly 90~100% for Infrared.
Some lens like the Prizm Trail lens has 36% VLT listed, but lets in a lot more light than that on the red end of the visible spectrum hence red, oranges, yellow, tend to pop much more vibrantly. Which is also why Prizm Trail can be considered uncomfortable for people who move between shade and bright conditions versus Prizm Trail Torch which has the red end evenly reduced closer to the rest.
Spectrum Charts from SportsRX Video : Oakley PRIZM Trail vs. Trail Torch