These are great if one of your lenses was scratched, cracked, the threads damaged, or lost. You don't have to replace the entire video baby monitor because you can just get another lens. The DXR-8 Infant Optics Video Baby Monitor comes with a default lens and can also use a wide angle lens and an optical zoom lens.
These lenses are made with multi-layered glass held in an aluminum housing.
About the different lens types
One of the coolest things about the DXR-8 Infant Optics Video Baby Monitor is the ability to change out the lenses.
The wide angle lens is good for being able to see a whole room if you have an older child that is able to move about. The wide angle lens has a 170° panoramic view.
The optical zoom lens is good for getting a close view in greater detail of a smaller area. The optical zoom lens is 2X and when combined with the digital zoom offers a 4X zoom.
Personally, I prefer to use one of each for a room. That way you've got a good way to keep an eye on the child while sleeping but if the child moves out of the viewing area, you're not at a loss and you can still see the room and if he is getting into something he shouldn't or making a mess.