Posting here as this is neither a flashlight headlamp nor power bank. It is all three?
FANDYFIRE L811 Headlamp/rechargeable/powerbank.
Some are labeled Longfire or nothing at all.
Headlamp has 3 levels. Hi. Lo. Flash/disco modes.
Charged via micro USB connection.
Can provide charging via USB cable to phones. (tested to charge my LG G2).
Multiple colors are available.
Price range from about $13 to hi $15 (us) in multiple chinese retailers.
Very well made. Heavy for it’s size.
Good Q headband is included. and rubber straps are strong and can be very tight around the body tube. Which is a good thing. Rubber strap that come in contact on your forehead will leave you with a good marring unless you have it on the hat/helmet.
Output on hi is very bright in the dark. Enough to work with it for long periods of time. Has a purple ring on white wall. But is not noticeable in use.
Capacity ratings are all over the place from 1500 to 2500. I have no way of testing the actual capacity.
Output is also rated anywhere from 100LM to 200LM. My getting old eyes V1.0 tells me it is about 150LM on hi.
Flashing is very fast and not ideal to be used as a flashing bike light. But good enough to be used as main illumination on hi. Just!
This would be a good item to leave in the car connected to a usb charger. To be used in an emergency, and to provide power to smart phones in a pinch.
Over discharge protection.
Guts (can not be opened, Can not be twisted off at least for now. May be in a vise with a big tool! End caps seems to be glued in and very very tight. Heat and vise may open it but it may also destroy it.).
The ridge on the light’s lens spills lights towards your face. I wear glasses and glare is very bad. So I taped small strips of aluminum foil below and above ridges and problem is solved. I can use it on lo setting to read very comfortably wearing it on my head or standing beside my bed pointing to the book. You can also wear it around your neck facing front as a task light. Very good.
If someone can organize a group buy, I would get 2 more as these seems to be very useful.
I hope that is useful to others on the forum as I have benefited from others reviews and advice.