Julbo's Bivouak model is a classically stylish frame with understated - versatile - good looks. It is also incredibly comfortable and solidly seated when on your face, so ideal for a variety of sports use.
The genius of the Bivouac is the removable blocks which sit at the top of the arms (the armpits?) to provide extra coverage and protection from glare which may sneak in at the periphery of the frame. Attached by magnets, these can be fitted and removed almost instantly, but if you're like me you'll likely lose them on the first removal! The frames look good with these blocks on or off, so maybe safest to leave them in situ!
As you'd expect from a category 4 lens, the sun is virtually switched off when the glasses are put on. You could probably observe an atom bomb without extra ocular precautions. But where the Cameleon lens falls down is in brightening up. Julbo claim this photochromic lens can vary from cat 2 to cat 4, and while the dark end is not in question, the cat 2 still blocks a lot of light.
It's important to understand the system for categorising lenses; Cat 2 technically means 18% - 43% light transmission, and the range of the Cameleon lens only just dips into this wide bracket. They're also polarised which makes them feel darker again.
Flat light, stormy mountain precepitation and dark lenses are not a safe combination, so it's essential to test out their limits before committing yourself to just one pair of glasses on the hill.
Julbo have still created a stylish, well built pair of sunglasses suited to glacier travel - albeit without quite the level of versatility you might expect.