I have 5 of these now, three brown and two black, all five still work, one does have a minor problem every once and a while it goes a bit dimmer but give it a little tap and it goes back to normal... I ordered my fifth one to replace it...Keep an eye on it.
I bought the brown version:
$5.38 1*LED 5-Mode Zooming LED Flashlight - 1*18650 / with clip / 15cm carrying strap / beam range 200m at FastTech - Worldwide Free Shipping
Left a battery in it(turned off) and after a week the battery was dead, 0volts nada.
I use it now to drain batteries before recycling them.
For the size of them, almost the size of a mech mod these things will blow a 80$ maglite out of the water... and you can get 16 of these for the same damn price...