Note: This article is titled impression, not review since I did not have enough time to review the product.
Redring is an optical sight designed for shotgun shooters. It attaches to the rib of a shotgun. It comes with a recoil absorbing mount that ranges from 5 to 11.5 mm. It is parallax free. The light-measurement system also adapts to background light. It also automatically shuts off after 4 hours.
The ring is meant for 65 ft zero. So if the target is in that ring, the likely result is that the spread of fired shotshell would be within the ring. Because of this, there is no sight adjustment dial. This probably is the reason why the height profile is not big.
According to their website,
Battery: AAAA 1.5V, Approx 300 h life.
Weight: 134 g (4.726 oz) excluding mounts, 192 g (6.773 oz) including mounts
Length: 134 mm (5.275 in), mounts included
Width: 44 mm (1.732 in)
Height: 45.7 mm (1.779 in)
Material: Anodised aluminium
It was invented by P-O Östergren, and made in Sweden.
My impression is that it is an interesting option. I am a novice when it comes to shotgun shooting and it was rather easy for me to hit the clay pigeons with Redring. As long as the pigeon was inside the reticule, it was a matter of pulling the trigger. Of course for pigeons that are moving across my field of view I have to have lead it, but It was very intuitive to shoot, especially since I was used to EO Tech sights.
One thing that might be a put off for some people is the price. Retail is supposedly around $800 - $900. It maybe a bit expensive for average shooter here in US, where as in Europe shooting is more of a rich man's sport. A part of me was wondering whether I could find a Picatinny rail and attach and EO Tech sight and get simliar result.
Ultimately, the utility depends on the user, so as more show up there will be more opinions to listen to. Here is a review from a British shooter.
Website: http://www.redringsight.com/