NUPROLs Killflash’s are designed to screw straight onto your chosen optic, over the object lens. The honeycomb structure provides two benefits. Firstly, incoming BBs have deflected away from your optic, preventing damage. Secondly, light entering the optic is reduced, minimising lens glare on those sunny days. Please Kill Flashes are regarded as sacrificial protection and should be replaced after being hit and damaged by a BB.