This adapter is designed to connect UltraFire X8 flashlights (which are practically the same as , but not identical to, TrustFire X8 flashlights).
To attach your flashlight to the projector, first remove the flashlight bezel by unscrewing it.
Bend the adapter slightly open (careful not to break it), so that you can put it on the flashlights head. When aligned correctly, the adapter will form a closed ring again.
Now you can screw the assembly into the projector, effectively locking the flashlight in place.