Julbo REACTIV photochromic technology immediately adapts your lenses to the prevailing light conditions for ultra-accurate vision, no matter the weather. Reactiv lenses are photochromic, in other words, they will transition based on the brightness of the environment you are in! Reactiv lenses are made of NXT (Trivex) which has the clarity of glass and the durability of an antiballistic material.
On the other hand, Spectron lenses are not photochromic, they will not lighten/darken. Spectron lenses are made of polycarbonate, which is shatter resistant and a versatile lens suitable for all types of activities.
Keep in mind, regardless of lens type, all of our lenses provide 100% protection from harmful UV A, B & C rays.