REACTIV lenses are photochromic and adjust to changing light conditions by getting lighter or darker depending on the amount of UV light present. REACTIV lenses are made of NXT (Trivex), which has the clarity of glass and exceptional durability and impact resistance. 

SPECTRON lenses are not photochromic and will not lighten or darken. SPECTRON lenses are made of polycarbonate, which is shatter resistant, and are a versatile lens suitable for all types of activities.

Visible Light Transmission (VLT) refers to the percentage of light that filters through a lens—the higher the number, the more light passes through. A window in a home, for example, might have a VLT of around 70%, allowing most visible light to pass through while filtering enough to keep your sofa from getting bleached. A typical goggle lens, like a home’s window, has a fixed VLT—the amount of light it lets through and blocks out remains the same, no matter how bright or dark it is outside. 

The VLT of Julbo’s REACTIV lenses, on the other hand, changes as ambient light changes. The new REACTIV 0-4 lens, which has the widest VLT range of any photochromic lens on the market, has a range of 83 to 5%. In other words, just 5% of visible light filters through the lens under extremely bright conditions, allowing for ultimate protection. Conversely, 83% of visible light filters through when it's dark out, allowing for total clarity. Regardless of VLT, REACTIV lenses filter 100% of harmful UVA, B, and C light.