Ended up going a different direction with optics, Here’s the description form the website. Fully protected TFO® technology encapsulated in a virtually indestructible capsule. Impervious to oils, chemicals, cleaning solvents, and ultra-sonic cleaning processes. Unmatched visibility in all shooting conditions 24/7. Assembled in USA with quality Swiss tritium for maximum brightness. Glows in the dark – no batteries or light exposure required. Front sight FOCUS. LOCKT for fast and accurate shooting. Concealed fiber cannot be seen by target. FORTRESS FINISHT nitride protective coating.