Julbo Density Reactiv Sunglasses – 0-3 Photochromic Awesome Shades

Julbo Density Reactiv Sunglasses - Drew Thayer of Engearment.com

Julbo Density Reactiv Sunglasses – 0-3 Photochromic Awesome Shades

Drew Thayer

Well over a decade ago I remember getting a raise and blowing it all on a pair of photochromic sunglasses because they seemed just so cool. Well, they changed in tint by about 2% when they sun went behind clouds and I remember selling them on Craigslist… I probably needed the cash for climbing shoes or something.

Fast forward to 2023 and photochromic lens technology has improved by light years – we’re talking about lenses that can automatically adjust from totally clear to dark enough to wear on snow in seconds. I’ve been testing the Julbo Density Reactiv sunglasses this spring with Reactiv 0-3 lenses and I’ve been blown away by the lens performance. The frame is light and fits great too, even on my small head. 


Julbo Density Reactiv Sunglasses - Drew Thayer of Engearment.com

Julbo Density Reactiv Sunglasses – Drew Thayer of Engearment.com – The Reactiv lenses in mostly-dark mode while setting up our camp in bright afternoon sunshine in the Gore Range.

Frame performance and fit

Density is a new-school sports sunglasses frame – full coverage and very lightweight. These are seriously light; I barely notice them on my face and completely forget after a few minutes, like any good sunglasses should.

The nose grip and sides of the frame are both coated in a light grippy rubber, not so thick or squishy that it bends around, but grippy enough that these shades don’t slide even if I’m dripping with sweat. They seem to vent pretty well too and avoid fogging, even on humid mornings without wind. A small vent port that’s barely visible at the bridge of the nose likely helps. 


The fit of these sunglasses is pretty versatile despite their large format. I have a kinda small head so I don’t usually go in for sunglasses advertised as large or “full coverage,” but the Density fits my face fine. This might have to do with the lack of sharp angles far out at the lateral edges or the fact that they are always somewhat transparent. Whatever it is, it works – these look good on small and large heads alike. 


I appreciate that these glasses fold fairly flat for a full-coverage frame. I often run and bike in the evenings and mornings and end up stowing my shades in a running vest chest pocket or a fanny pack if mountain biking. It’s much easier to fit a flat-ish pair of glasses into these small compartments – the big old-school wraparound-style glasses (Oakley’s etc) just don’t fit.


My only gripe (and this could be specific to my face) is that the high center part of the lens is close enough to the bridge of my nose that it will get smeared with sunscreen. This isn’t that big of a deal because I can’t normally see it – I just need to remember to wipe it away so I don’t get so much built up that it smudges or runs onto the main part of the lens. I’ve developed the habit of somewhat neurotically wiping them every time I take them off, but then again I’m pretty obsessive about clean sunglasses so it’s nothing new. 

Julbo Density Reactiv Sunglasses - Drew Thayer of Engearment.com

Julbo Density Reactiv Sunglasses – Drew Thayer of Engearment.com – Scrambling the First Flatiron on a partly cloudy day, the Density glasses felt great on my face and Reactiv lenses kept adjusting to light conditions. Here, they sat somewhere in the middle of their tint range and thin clouds blocked the sun, while making the colors of the pine trees and red sandstone appear really vivid.

Lens performance


I’m just going to say it. Wow. 


The Density shades come in a variety of frame colors and lens configurations, including Spectron (less expensive fixed-tint polycarbonate lenses) and Reactiv (photochromic), which are both lightweight and shatter-resistant. I tested the Reactiv Category 0-3 lenses, which vary between 12% and 87% visible light transmission. Grok those numbers for a second… that’s from effectively clear to dark enough to wear in the snow. Amazing! 


Out of the box, these glasses seemed to cover the ranges of light encountered in running and cycling, but I ski in the backcountry a lot, and I was skeptical that a photochromic lens that went all the way to Category 0 (clear) would really get dark enough to wear in the snow. In early May I embarked on a 4-day exploratory mission on skis into the central Gore Range to scope the beginning of the corn cycle and hopefully catch some late-season powder skiing.

I wore these Density Reactiv glasses but carried an older pair of Category 4 shades as a backup since glasses that aren’t dark enough are a liability during long days in bright sunlight on snow. I never ended up taking the backups out of my pack – these Reactiv 0-3 lenses were comfortable to wear in the morning sun glaring off miles of frozen white crust and transitioned seemingly instantly as clouds blocked the sun and even pelted us with snow. 


I consider these Reactiv 0-3 lenses good for pretty much all light conditions one might encounter, from local trails at dusk to bright sun at 13,000 feet. I’d still probably bring a Category 4 lens on a glacier mountaineering trip where the light is going to be glaring all the time – but that’s a really specific application. 


An additional benefit of these Reactiv lenses is that they really help colors pop. The tonal richness of greens and reds in lower light is surprising; in fact I’ve ended up keeping them on while running into the afternoon as clouds build (I usually take my sunglasses off once it’s not bright anymore) just because they make everything look more vivid. Awesome technology. These shades now live in my running vest and go on all my bike rides and spring ski tours too.

Julbo Density Reactiv Sunglasses - Drew Thayer of Engearment.com

Julbo Density Reactiv Sunglasses – Drew Thayer of Engearment.com – Density glasses with Reactiv 0-3 lenses in their nearly-clear state, running in the forest with clouds covering the sun. The lenses start to get a tint darker and help colors pop once you can see a hint of a shadow on the ground.

Bottom Line

New-school style, full-coverage, and very lightweight sports sunglasses available in a variety of lens options at a very premium price point (I tested Reactiv 0-3, which spans just about every light condition except for glacier mountaineering). Fit a variety of face sizes, and they avoid fogging well.


Don’t buy these because you need sunglasses – you can get great sunglasses for fifty bucks. Buy these because you want to revel in the visual clarity and chromic splendor of the spaces you move through.

Drew Thayer

Julbo Density Reactiv Sunglasses - 0-3 Photochromic Awesome Shades 1

Drew’s love of gear is born from his life-long obsession with human-powered adventure in the mountains. On foot, on ski, on bike, and on the steep rocks, he loves exploring Colorado’s mountains through each season.
Drew brings a technical eye to gear — he’s a data scientist with a Masters’ degree in Geophysics and loves to understand the design and engineering make great gear what it is. He’s also worked in the field for many years — as a wilderness therapy field guide and a Geophysicist — and knows a thing or two about function and durability of technical equipment.
Drew tests gear in real mountain conditions, on overnight ventures whenever possible. His specialties are rock/alpine climbing and light-and-fast human-powered pursuits on ski or mountain bike. He’s ventured on exploratory climbing expeditions in Argentina, Peru, and Alaska, and completed remote technical river descents in Alaska and Colombia.
When not building statistical models and writing code, he can be found tending his garden or trying to keep up with his awesome wife.
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