M4 Tritium Night Sight Inserts for Ghost Ring Sights. Designed to fit M4 shotguns manufactured after 1997, these Tritium three-dot inserts can be easily installed into the military spec ghost-ring sight. When the lights go out, you'll have the advantage with these ghost-ring tritium inserts. Features: Tritium Night Sight Inserts Fits: M4 Ghost Ring Sights (Manufactured After 1997) M2, Nova & SuperNova Ghost Ring Sights (Manufactured After 1997) Note: It is recommended that all parts be installed by a qualified and trained gunsmith. Mfg: Benelli