This is an attachment for Fenix TK-series flashlightings which owns outstanding filtration ability to maintain strong red light only. With its high penetrability for fog and smoke, it could be used as singnal lamp or when necessary.Features:Color: RedEasy to attach, easy to remove39.7mm diameter,25mm heightCompatible with all Fenix TK-series flashlightsTechnical Specification:User a toughened ultra-clear glass lens with anti-reflective coating that provides heat resistance and maximum light penetrabilityMade from PC 2805 plastic created by Bayer Material Science AG,work great for Anti-aging,anti-press and anti-impact