Surefire F27 Blue Filter for 1.25" Diameter Bezels
The F27 filter produces a smooth beam of blue light. Hunters use the blue filter to track wounded game at night because blood stands out more distinctly against foliage when viewed under blue light. The filter is also useful for close range applications such as map reading as it reduces light output and helps preserve night-adapted vision. Flip-up filter window allows instant access to white beam.

Fits: All flashlights and WeaponLights with a 1.25" bezel