Meprolight FT Bullseye Sig Sauer P320 (Not M17/M18) Front Sight - Green - The Fiber-optic Tritium combination enables instant and accurate shooting in all lighting conditions with no batteries needed. The Fiber-optic used in bright light or day shooting and the premium-grade Tritium provides instant illumination at night or in low-light conditions. Smallest optical sight in the world based on patented optical illumination Superior visibility in all lighting conditions No front sight needed Fast and intuitive target acquisition Fits most existing holsters