DayZ field wiki · Gear
Gun light
A tell
Short answer
It shows the hallway and you. A chemlight on the floor is quieter politics.
Also: weapon light · tactical light
How it works
Weapon lights attach and eat batteries. People see the beam. Infected may too.
What to do
Pulse it. Don't leave it on as a lighthouse.
Don't
Don't clear a barracks as a searchlight.