I was amazed when I pulled the cap off because I honestly could not see the glass in the filter itself. No matter how I angled and turned the outer ring the glass reflected nothing. It wasn't until I put the cap back on preparatory to screwing the filter onto my lens that the inner surface of the cap reflected a light directly above and enabled me to see the inner glass.

I installed the filter onto a standard Nikon 50 mm lens and putting aside the question of whether to use this type of uv filter to protect your lens I have noticed no distortion or light cast in photos. Because the filter has matching 52 mm thread on the outside you can stack filters on top of it.

The only problem I experienced was with the magnetic lens cap which, actually, was the main reason I ordered the filter and which I imagine is their big selling point for this line of filters. The problem is taking the cap off the filter - because the grooves on the outside rim of the cap are horizontal to the plane of the lens there is no way to easily grip the cap and pull it off. K&F should have used raised horizontal striations which would allow easier gripping and removal of the cap. After a while shoving your fingernail into the very small groove between the lens and cap gets tiring and takes longer to use than the industry standard push in tabs. On the other hand the cap snaps onto the filter quickly and securely. I have tried to show these 2 factors in the short attached video.

Other than the aforementioned issue with the cap this line of K&F filters with magnetic caps are a really good fit for your photography and the K&F Concept line is frequently recognized as a high quality product. I give this K&F Concept filter with magnetic cap a solid 5 star rating.