Meprolight FRBS M2D Front and Rear Set of Flip-up Sights with Tritium (2 Rear Dots, OD Green)The Meprolight FRBS are tritium enhanced, self illuminated front and rear back up sights designed to provide the shooter secondary sights in case the primary optics go down. The FRBS sights are advanced, low profile, durable, tritium enhanced auxiliary front and rear back up sights. The sights quickly fold up or down depending on the shooters needs. Sight pin elevation is easily and quickly adjusted without tools. FRBS sights are readily mounted on