It is a lightweight headlamp that, however, will not make your night into day.
I use it for night fishing where I have used several flashlights.
Among the advantages of the flashlight, I will rank its small weight and the various lighting options (beam_field_colors, etc.), as well as the adjustable brightness, something that I also mention in its disadvantages, specifically that the flashlight starts at 50% of its brightness when turned on. To increase the brightness, you hold down the button and after it goes through the entire 'scale' to its minimum, then it starts to increase the intensity. However, when you turn it off, it starts again from 50% and goes back to the beginning.
I used it with the batteries included in the package and it lasted for 4 nights (not at maximum intensity), with the last two nights having a continuous battery indication and reduced brightness compared to the first two nights.
I also used it with rechargeable batteries (800mAh), but with those, it barely lasts for one night.
Among the disadvantages, I will also include the soft plastic gear it has for adjusting the angle. I think this will break early, with a sudden jolt (e.g. a small on-site jump can change its angle by one click).
In conclusion, for its price, it is a decent flashlight, you won't regret it and it won't leave you in the dark. However, if you want something really bright, look somewhere else.

Once I was very hesitant about buying a headlamp. I was thinking about the weight, size, and how convenient it would be on my head, especially for long hours of work.
This particular headlamp is worth it and more.
1. Made of plastic (a possibility that I cannot evaluate how durable it will be in case of falls or use) but those who made it wanted the lightest weight for someone who wants to use it for hours. It is convenient, easy to use, extremely lightweight, and its angles are easier to focus on (unlike the previous generation that gave the impression that the lamp would break with every change of angle - as I saw in some videos).
2. It provides powerful illumination at the first level and at 400 lumens. Its toggle buttons are user-friendly, both for brightness and for switching between red night vision and green illumination (which is wonderful).
3. Finally, it works with rechargeable AAA batteries!!!! I have tried many headlamps with rechargeable batteries, but they couldn't work. Their LEDs needed a voltage of 1.5V to turn on, and at 1.2V (which is usually the voltage of rechargeable batteries) they couldn't work well enough. Fortunately, they work flawlessly with this headlamp.
4. If the operating hours stated on the packaging are true (using Energizer MAX Alkaline), then we are talking about the ultimate gadget for fishermen, camping, household chores, emergencies, and any situation that requires long hours of work with lighting. 2.71 hours at 400 lumens (the first level in the selection) and 50 hours at the lowest level (with both lamps lit at minimum brightness).
2 buttons:
1st button: 1st press: / 400 lumens with two LEDs. 2nd press: -50% brightness with one LED lit. 3rd press: 2 LEDs lit in dim mode for lower power consumption. Long press: 2 LEDs lit, adjusted to the lowest brightness.
2nd button: 1st press: Red night vision illumination. 2nd press: Red night vision illumination in SOS mode. 3rd press: Activation of the green LED.
Okay, I will probably go for a second one: one for home and one for my work.

[EDIT]: I bought a second one for my work and I don't regret it. Both products that I received stated that they are 450 lumens (instead of the 400 mentioned in this specific description). Nevertheless, it is a commendable product and it performs its job perfectly in all lighting conditions. What remains to be seen now is its autonomy... and I will come back with comments about it once I test it in all conditions.