The flashlights are junk
you can buy better ones for less money
Go with Samsung, Sony, LG, Panasonic or Sanyo 18650s you get 3000-3500mAh with low resistance
as those Ultrafire batteries are junk labeled 4000-8000mAh but in reality 300-600mAh and very high resistance
if it has to be a zoom light go for this one
https://www.gearbest.com/led-flashlights/pp_263535.html
The Zanflare Z1 was on sale for 12.99$, but thats ended
still a good light
https://www.gearbest.com/led-flashlights/pp_536609.html?wid=21
review
or
a bit higher build quality
https://www.gearbest.com/led-flashlights/pp_20323.html (link is external)
$ 29.99 with the coupon : P16SS (Effectivr Code Now!!!)