The Bottom Line: The Teqin headlamp is a great choice for short trips and low budgets. It's extremely low cost, it's waterproof, it has multiple modes, and it works well. However, due to its rechargeable battery, you will need to buy a more expensive headlamp for more serious trips where greater reliability is required.
The Teqin is a great cheap, rechargeable headlamp with a sleek design. It's lightweight and compact, yet it is fairly bright at 90 lumens and has two power levels - a focused bright level and a wider and dimmer low-power level.
The rechargeable battery was the reason I bought it. Not having to buy and replace batteries is fantastic, and it's exactly what I wanted. However, I sometimes worry that the battery will run out while I'm on a trip. There is an indicator LED that is red when charging and green when fully charged, plugged in. However, there is no way to tell how much battery life is left. Additionally, the Amazon page lists no battery life specs, which made me a bit nervous to purchase it.
With that all said, I have never had it run out of juice. It has lasted me on several four- to six-hour trips in the dark with no problems. And as I mentioned, there is also a lower power, wide-angle mode that will stretch the battery life longer. I did a simple battery life test and found that it lasted five and a half hours on high power mode without dimming. At seven and a half hours the headlamp dropped into low power/wide mode, and by 12 hours it was still going but was quite dim. The lamp also charges with a simple micro USB port, so you can charge it from the same battery pack you use to charge your phone. I often carry a battery pack when I hike anyway, which alleviates the battery anxiety.
It's fairly comfortable and has an adjustable head strap. The light also tilts down for more flexibility. Additional features of the Teqin include a blinking/strobe light - which is easy to accidentally turn on by holding the button for a few seconds. It's also rated IPX6 waterproof. I've hiked in the rain with it a few times and had no trouble.
For only $10, the Teqin is a great choice for budget or casual hikers and one-night campers. However, because it's not a well-known outdoor brand and because of the battery considerations, you'll need to spend a bit more on a good quality name-brand headlamp if you need more reliability.