SureFire F26 and F27 filters slip onto the bezels of select SureFire models. These filters can be flipped open and out of place when white light is needed. Both the red and blue colors can be used to preserve a user's scotopic vision. The F26 (red) filter improves contrast and aids in reading red-light readable topographic maps. The F27 (blue) filter assists with identifying fluid on dry surfaces (e.g. tracking blood on a hunt or finding a leaking source of fluid in an engine bay). F26 and F27 filters fit bezels 1.25-1.39 inches in diameter. F26 and F27 are sold separately.