Holosun HE509T Enclosed Pistol Reflex Optical Red Dot SightSpecifically designed for pistols, the HE509T RD features an enclosed design that protects the emitter within sealed tubes, so it can't be obscured by water, mud, and dust. The body is made from Holosun's Grade 5 titanium, which provides more than double the tensile strength and as high as 5X the fatigue strength of aluminum. It's a tough Red Dot Sight, but what's on the inside is what matters. Inside the HE509T are a few of Holosun's most advanced