K&F ConceptAdjustable Iris Aperture Diaphragm M30 to M37 Iris Aperture Diaphragm Adapter Optical Diaphragm 1.5-26mm Lens Module Adapter Ring Optics PVS-14 PVS 14 Optics (M30/M37*1)

So I do not have night vision goggles but I love mechanical iris's. I even printed all the parts for one and built it myself. But this one is miles better than anything that comes off of a 3D printer. Really it is the mechanical iris from a lens, only exposed. The outer ring turns very smoothly and has just the right amount of resistance to let you confidently stop it at any aperture. I am going to use this mostly to show my friends, but eventually I have a project in mind for it. Very cool part and definitely great quality.

I gave this product 5 stars because it worked as designed. The shutter mechanism is quite smooth and easy to adjust. In fact, I found it easy to adjust the aperture than the gain on the optic.While this product worked as designed, I am not sure that I will continue to use it often in the future. While you can open and close the aperture without affecting focus, I tended to over crank things and would often end up slightly out of focus which I found annoying. I understand this may be user error, but this is my user experience. Also, the aperture moves quite smoothly and easily which is nice for the user, but is also easy to brush against it and unintentionally change the aperture. Maybe some light detent settings would have helped?Overall, the product seems to be made well and functions as designed.

If you have a project that needs an adjustable aperture, such as playing with your own lens and camera designs, this is a winner. It's very smooth and easy to adjust the size of the aperture and the amount of "blades" make for a very round opening.