Basic - Press on the switch button until it clicks to turn on the flashlight. Press the switch again until it clicks to switch off the light.
Access output groups 1 & 2 - Tight the head to access group 2 output. Loose the head to access group 1 output.
Switch between output level - With the flashlight on, slightly press the switch and release (within 1s) to switch to the next output.
Energy saving feature - dim or increase the entire output range of the group 1 (head loose) output. Toggle this setting starting with head loosen, turn on the light, and then repeat tight and loose for three times.
*The output difference between the two lowest output (with this feature enabled and disabled) is about 25%, you may need to pay extra attention to see the difference.