True to its name, the Killflash is designed to prevent reflections which might potentially reveal your position to the enemies. For airsoft use, it protects the lens from hits. Its metallic, honeycomb mesh design is very thin yet deep. It allows for a clear view, and won’t interfere with targeting even in dim environments, unlike lens covers made of perforated metal sheet!
The killflash honeycomb is not a 100 % protection for the lens. A BB may split when hitting the honeycomb and a piece may still break the sight lens. According to user experiences, a killflash works usually well as a lens shield, but because there still is a possibility, even though a small one, that the lens will break, a honeycomb is not a 100 % certain protection for the lens and therefore warranty will does not cover a broken lens.