The top optic is a Darkstar NV-224 night vision scope, below it is a AN/PVS-4 for comparison. The company that made it, Tactical Night Technologies is long out of business.
This scope uses the same image intensifer tube as the PVS-4. While these tubes were made as Gen 2 and Gen 3 models, as far as I know all the Darkstar scopes are only Gen 2s. I’ve heard people claim that the PVS-4 tubes are some of the best and most capable of the gen 2 night vision devices and I believe them. That said, these are a product of their time and are large and heavy.
At 4 pounds and nearly 12 inches long this is not a small optic. I tried doing some rapid target acquisition and firing at 50 yards and I found the scope very slow and awkward for that purpose. Usable, but far from ideal. It would be better for use in a stationary position off a rest or support.
It runs off two AA batteries. On this particular one the plate for the batteries has broken loose and has to be popped back in place for the scope to work. Battery life is suppose to be 20 hours, but I didn’t get the chance to test that.
An Elcan mount provides the ability to attach this scope to a Picatinny rail and all zeroing is done on this external mount. Once zeroed, the dial for elevation and be adjusted for 300-800 meters.
Operation is simple. If you are using it during the day, you leave the protective cover on the objective lens. At night you remove it. There are a couple of brightness settings on the power switch. By the objective lens there is a focus for target clear, and by the eye piece there is an Eyepiece focus. I was able to clearly see the target and the environment. Unfortunately the pictures above do not do the sight justice.
The Darkstar objective lens.
The rubber eye piece cover has a shutter in it that opens when you press your face up against it.
Overall I like the Darkstar NV-224, but it is old and obsolete. If you can find one cheap I think it is worth while, but it just is not competitive with more modern night vision devices.
A copy of the manual and some additional information is available here.