The Meprolight Fiber-Tritium Bullseye Sight for Glock MOS Rear Sight Red, ML63105R Gun Make: for Glock, Gun Model: for Glock 17, for Glock 19, for Glock 22, for Glock 23, for Glock 24, for Glock 26, for Glock 27, for Glock 31, Color: Black, Front Sight Color: No Front Sight, Rear Sight Color: Red, Fabric/Material: Fiber, Metal, Tritium, Gun Type: Handgun, Attachment/Mount Type: Dovetail, Illumination Type: Fiber Optics, Tritium, Illumination Color: Red. 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 Simple, easy installation on existing pistol dovetail No Batteries - No Switches - Always On- Always Ready