Holosun 503CU Red Dot Sight with Solar Backup for Rifles

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Holosun 503CU Red Dot Sight for AR-15

The Holosun 503CU comes out of the box packed with features, with a pre-installed mount perfect for your AR-15. This red dot uses all of Holosun’s innovative features, including a switchable circle dot reticle, Shake Awake, and a Solar Failsafe to keep this dot running – even if you manage to run the battery dry. The 503CU features 0.5 MOA windage and elevation adjustment for precise shooting.

The Holosun circle dot reticle also makes getting on target fast and easy. By zeroing the 2 MOA red dot at 50 yards, you can effectively use the 65 MOA circle to estimate range, or make point-blank shots using the bottom crosshair. This red dot enhances your capability as a shooter, and it’s ready whenever you are, with a battery life measured in years and proven reliability.

Red Dot or Green Dot?

Holosun makes this sight with a red emitter, or a slightly more expensive green emitter. As for which one is right for you, it depends. Both models have the same features and incredible battery life, though some shooters prefer the green dot because it catches their eye faster than the red reticle.

One thing to consider is your shooting environment. If you have a lot of green in your background, the red version will provide you with better contrast. In arid environments with reddish soil, the green reticle will stand out more. It depends on your eye and your situation; but in our experience, it’s down to personal preference: you can’t go wrong.


  • 50,000 + Hour Battery Life at Lowest Settings
  • Shake Awake to Extend Battery Life Even Further
  • Solar Failsafe – As long as you have sunlight, the sight will run!
  • Multi Reticle System – Choose from three different reticle modes
    • 2 MOA Dot with 65 MOA Circle
    • 2 MOA Dot Only
    • 65 MOA Circle Only
  • 10 Daylight Settings and 2 Night Vision Compatible Settings


  • Lower 1/3 Cowitness Mount
  • Low Profile Mount
  • CR2032 Battery
  • T10 Wrench
  • Rubber Lens Cover
  • User Manual
  • Lens Cloth


  • Magnification: 1x
  • Lens Diameter: 20mm
  • Parallax Free: Yes
  • Eye Relief: Unlimited
  • Light Wavelength
    • Red: 650nm
    • Green: 540nm
  • Battery Type: CR2032
  • Battery Life: 50000 Hours
  • Adjustment Per Click: 0.5 MOA
  • Windage/Elevation Range: ±50 MOA
  • Waterproof Rating: IP67
  • Vibration Rating: 1000G
  • Storage Temperature: -40 to 70 Degrees Celsius
  • Working Temperature: -30 to 60 Degrees Celsius
  • Housing Material: 6061-T6 Aluminum
  • Dimensions
    • Height: 1.6″
    • Width: 1.43″
    • Length: 2.6″

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

Your Holosun product is warranted to be free of defects in materials and workmanship to the first owner upon registration of the product. This warranty specifically applies to the metal structure, optical and illumination systems. The metal structure/housing and optical system (glass) of your Holosun product is warrantied for the life of the product under normal, personal use. Under the Holosun Warranty, the illumination system (LED), is warrantied for 10 years from the manufacture date under normal, personal use. In the event of a confirmed defect under this warranty, we will, at our option, repair or replace the product with a Holosun product of similar type/function, and of equal or greater value. Holosun reserves the right to make substitutions for similar product/s if the warrantied model in question is no longer in production. This Holosun Warranty does not apply to: (a) asserted defects caused by normal wear and tear of any part including knobs, finish, etc.; (b) asserted defects caused by modification including; aftermarket finishes, unauthorized service, improper maintenance, acts of Nature; and (c) asserted defects involving subjective personal likes or judgments. Also, this warranty is null and void if modification or maintenance is provided by someone other than Holosun. Holosun may restrict warranty service for our products to the country from which Holosun or its authorized dealers originally sold the Holosun product. For warranty claims outside the United States, the costs of shipping or transporting the product (including to and from Holosun or our dealer), any insurance or any fees, duties and taxes are the sole responsibility of the purchaser and will not be covered by this warranty.

Registration is required to validate this warranty. For product registration click here. For a warranty claim, click here.