If you like the styling of real steel holographic sights, the Delta Armory Holo-551 Style Red Dot Sight is one to watch. Patterned after the real steel 551 holographic sight, the Holo-551 is the shorter alternative to the Holo-552, ideal for compact platforms with limited rail space. Boasting an integral 20mm Picatinny rail mount, red and green reticle illumination with 5 brightness levels for each colour, the Holo-551 provides the same superb utility as the Holo-552 without wasting space on your primary. 
 
Features
Integral 20mm Picatinny rail mount - Compatible with 20mm rails 
Compact version of the Holo-552 - Great for short platforms with limited rail space
Red and Green reticle colour options - Use the "NV" button to scroll between
Iconic "Holographic" looks - Give your primary the elite look
Aluminium protective shroud - Gives the sight extra drop protection
Rear-facing on/off & brightness control buttons - Easily accessible from a firing position
Windage and elevation adjustable via flathead screws on the right side - Zero to perfection!
5 Brightness adjustment levels for each colour - Set the brightness to suit the environment
Battery: 4x LR44 Button Cell (not included)