I've become a huge fan of K&F Concept. It's hard not to take the cost of this series of filters into consideration. This is the first filter from this series I have gotten, all the others have been either the Nano or the top-line series.

The filter is almost disappointingly lightweight, especially in the 52 mm size I got. It has very deep ridges on it, that really help with the grip—and, they do not add to the overall diameter, so if you have a slide on cap or hood, they will not interfere. It is also very thin, which is a good thing—but is also my only complaint with the filter—the inner threading (on the front of the filter) is too shallow to hold the OEM hood that is designed to work with the Nokton lens that I'm using it with. It sort of holds it, but there's some wobble and a bit of play, so I'm bummed about that. I tested it against the ~10 year old "pro" level German MRC filter that has been on that lens since I got it, and it is visibly a better filter in terms of overall contrast. (The hight level filters from K&F are even better in this regard.)

And, for this great price, you get a lens cap and a sealed cleaning cloth. The lens cap, which I have bought separately;y also, was the first K&F product I used that I felt was a flawed design, and this smaller one is also—while the recesses for your finger tips are plenty deep on the cap, the surfaces you pinch to use the cap are completely smooth, and I have trouble using them. I've been able to fix that by gluing a very small (~ 0.02 x 0.06) plastic strip along the side edges of the pinch points, which makes these work really well.