HD101AJ red dot sight for 20mm rail

33mm multi-coated objective lensReflex sight with 33mm lens provides a wide field of view for fast aiming.Multi-coated scratch-resistant amber lenses enhance image clarity, anti-reflective lens coating increases light transmission for brighter vision, and comprehensive multi-coating protects against scratches and scuffs and provides bright, clear vision image.4 tactical reticle optionsThe illuminated reflex sight features 4 bright reticle options, providing a variety of options to suit different situations. Red dot, circle/dot, reticle/dot and reticle/circle/dot combinations all in one sight that works with your existing iron sights.Parallax correction and unlimited eye fatigue reliefNo matter which way you shift your sight, the target's position on the crosshairs doesn't change, improving aiming accuracy.7 brightness settingsFeaturing 7 levels of brightness adjustment, the red dot sight can be adjusted to fine-tune your vision from sunlight to dusk. Button design makes brightness adjustment easier. Press and hold the button for 5 seconds to turn it off.