The Headlamp 425 from Biolite is a lightweight, rechargeable headlamp with bright front and rear LEDs, and the most comfortable strap that I’ve ever tested. My review:
The Headlamp 425 is a lightweight headlamp with a maximum light output of 425 lumens. If features white LED front lights with both wide angle and spot functions, as well as a red LED rear light with a laser and strobe mode for visibility. There is a single power / function button on the front with a separate button on the rear to control the red visibility LEDs. The front LED panel can be angled forward and down to accommodate various use conditions. The unit is powered by a sizeable USB-C rechargeable battery pack located on the rear of the unit that features and LED based power level indicator. The batter pack is connected to the front unit via an elastic power cord that runs along the outside of the band. It features Biolite’s 3D Slimfit technology, has an IPx4 water resistance rating, weighs 2.75 oz (78 grams), can can run for up to 60 hours on the lowest, and retails for $59.95.

The biggest boon of the 425 is the extremely impressive comfort level of the headlamp as a whole. I can only compare it to the sensation of wearing a ball cap, where there is clearly something on your head, but it is so unobtrusive that the sensation quickly fades away into non-existence shortly after putting it on. This is achieved by using their unique 3D Slimfit technology where, somehow, the body of the housing blends into the fabric strap perfectly and seamlessly. It is almost as if the engineers found a way to mold the band around the housing into one smooth, soft surface that perfectly distributes the weight and pressure of the components across the forehead and around the skull. This is combined with a impressive weight balance between the front lamp unit and the rear battery compartment, which keeps the headlamp from feeling weighty or off center. The materials are soft, smooth, and feel nice against the skin too. The end result is something that feels much closer to a sports headband than a headlamp and really surprised me throughout my use with it. Even jogging, where I had to tighten it down a bit more to keep it from shifting, was no problem at all. Very impressive here.
Using the 425 is surprisingly easy. The front button turns on the lamp, with following clicks cycling through the red flood, white spot, white flood, and strobe functions. The light can be dimmed or brightened by holding the button down once it is turned on. The rear button does basically the same thing and can also be dimmed. The angle adjustment of the front lamp is as simple as using a single finger to rotate the front lamp forward. Two buttons that are used in an obvious, logical way. This I like.
On the low output mode the 425 can theoretically run for 90 hours on one charge in perfect conditions, which is quite impressive. Alternatively, it can push an appreciably bright 425 lumens for 4 hours, or just about any combination in between thanks to the adjustable brightness function. I found low to be usable in close quarters, particularly in a tent for reading or similar tasks, while a medium brightness was generally enough for working on things, cooking, or even hiking. The highest mode I rarely felt the need to use, but would be handy for foggy nights or while jogging in poor lighting conditions where you may want to see further out in front or just be extremely visible. It is charged by connecting basically any USB-C cable to the rear housing which is protected by an extremely secure silicone cover. The unit seems to hold its charge well over long periods of non-use, which is a definite plus. It also supports pass through power, so one can connect an external battery and run the lamp it while charging.

Construction and durability are both excellent here. The plastic body is light-weight yet durable with solid seals to keep out water. The molded bands have held up well to being stretched to their limits, being wadded up and packed and getting wet and drying. The stitching is solid and fairly consistent too, providing a sense of security and reliability that I appreciate. The buttons and adjustments all have a solid, mechanical click to them that both sounds and feels quite satisfying to use and show no signs of wear after use.
A little bit of weirdness came with my unit in the form of the adjustment mechanism. One of the side tensioners was actually assembled reversed, which made adjusting the tension and positioning really inconsistent and tricky. It took me some time to realize something was wrong, and correcting it wasn’t that easy either but I did figure it out. I had to almost entirely disassemble the bands to put it back together properly. Afterwards, adjusting it is simpler than it looks. Basically, put it over your head and pull the tensioners and it cinches right into place. Not sure if all units will be assembled incorrectly or if it was just my unit so keep an eye out for that.
My only real complaint is that, as far as I can tell, the battery isn’t easily user replaceable, if at all. There is a sticker on the back that may be removable to reveal some screws, but I haven’t been down that route yet as it will likely have an effect on the water resistance.

Overall
I really like the Headlamp 425 from Biolite. It is the most comfortable headlamp I’ve ever used, easy to operate, and has a great battery capacity that is sufficient for hiking, backpacking, jogging, or just about any other excursion. Paired with the excellent build quality, low weight, and fair pricing at just $60, and suddenly we have one of my new favorite headlamps that I can recommend to anyone. Because of this, it is achieving my highest possible rating.
Highest of Recommendations
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