This flashlight comes in a blister pack with,
a)
One rechargeable 3,7V 320mA AAA sized protected Lithium Ion battery -- in common parlance ICR 10440 battery. (It will be slightly longer than the regular Alkaline or Zinc Carbon battery of AAA size, because of the protection circuit).
b)
One 1.5V Alkaline battery (Inside the flashlight)
c)
USB plug Charger for the Lithium battery.
d)
Lanyard (wrist strap)
e)
Holster (pouch)

You can't get a better & more compact keychain sized Lithium battery ...