3-dot sight system. Gives shooters 5x greater night fire accuracy. Patented shock-resistant design used exclusively by Trijicon. Glowing Traser tritium gas-filled lamps are warranted for full 12 years. Precision machined metal body. Polished sapphire windows impervious to solvents & puncture fitted inside the aluminum cylinders that contain & protect the glass lamps. Large front dot for extra distinction & brightness. Inlaid white paint rings. Silicone rubber cushions the glass lamp.