Red Dot Lens Positioning: All red dot sights have an objective lens at the front of the unit that is spherical in shape. However, unlike a conventional riflescope, the objective lens in a red dot sight is positioned off axis and appears to be tilted when looking at the sight. This angle of the front lens allows the light generated by the battery powered LED light source inside the unit to be reflected back into the sight. The reflected light becomes the “dot” or aiming reference that the user sees when a red dot sight is switched on. This engineered “bending” of light is what makes today’s red-dot sights so popular and easy to use. Adhesive is used on the inside of the sight to secure the LED to the inside of the tube. By design, the led package intrudes slightly on the field of view.