The functionality of the FlashShield is three-fold:
1) Kill flash function: Blocks reflections off the lenses that may otherwise expose your position to your target.
2) Sunshade function: Helps reduce glare, easier to see objects in bright light conditions.
3) Lens Protection function: Helps keep dust/particles from easily getting directly to lens.
The FlashShield easily clips-on to most full-size binoculars and riflescopes (32mm-43mm). They are lightweight, easy to attach and there is no need to worry about threads. The FlashShields are a must-have piece of gear for the serious hunter.