To open the battery compartment, unscrew the part with the orange power button. Once unscrewed, it should look like the picture above.
Use a AA standard battery or a rechargeable 14500 3.7V battery.
Insert the + side of the battery first
Screw the cap back
Power the flashlight to verify that it is working
To switch between modes (high beam, long battery life and strobe), you need to press the orange button, then press half way on the orange button
To get a denser beam of light vs a wider and more diffuse lighting, just move the front barrel with your fingers. It will slide as you produce a very blinding and long reach ray of light. This flashlight is short and very lightweight. This means it is easy to carry. You may want to keep one in your car, in your bug out bag, in your EDC bag and in your pocket especially when walking in dodgy areas at night. It is made of a very solid type of aluminum, has a great grip and has sharp edges. This means you can use it to get out of unfriendly situations by hitting and escaping.