They are intended for object observation and sighting shooting at dusk and night.
They are usually night monoculars supplied with the mechanism of mounting on the weapon and adjustment mechanism, a special mark within eyeshot of the NVD which has a role of "foresight". At finding the range the mechanism of adjustment provides overlapping of the hit point of the bullet with the target. In connection with heavy impact loads arising at a shot (up to 500 g and higher), there are made increased requirements for the shock resistance of sights.
Sights can be structurally made by combination of day and night sights. These are day - night sights.
As night sights you can also use usual day sights by mounting of NVD (night heads such as monoculars) on the input or output of the day sight.
For performance of night sights function you can use sighting complexes consisting of goggles and laser target designator. The laser radiates in IR range. It is fixed on the weapon and adjusted so that the optical axis of the laser and the hit point of the bullet would be coincided. The observer in goggles will see the point of the laser target designator. The aiming will involve aiming of this point at the observable object.
Instead of goggles you can use monoculars which are fixed on a helmet - mask.