I have been using K&F Concept filters for several months and I have been very happy with their quality. This set of a UV filter, circular polarizer, and two lens caps is excellent quality and is very reasonably priced. In terms of optical quality, I can't fault these. They are top-notch, and easily comparable in quality to Tiffen filters.

The filter frames are made of aluminum alloy, which is strong and light; they screw on pretty smoothly but aren't quite as smooth as the heavier brass rings that you get with more expensive filters. Brass is a naturally less "sticky" metal but these aluminum frames work just fine, especially because they have sections with machined grooves on each side that provide excellent grip for your fingers to grab on to when screwing and unscrewing the filters. I usually rub a bit of finger grease along the threads every now and then just to provide a light bit of lubrication.

The screw-on lens caps are beautifully machined and provide excellent protection, but they won't be replacing my standard snap-on plastic lens cap for everyday use when I'm out shooting because I find that having to screw and unscrew a lens cap is too time consuming and fiddly. The polarizer filter and UV filter can, of course, be used with any standard snap-on lens cap - you don't have to use the screw-on ones.

These filters come beautifully presented in a foil-embossed flip-open cardboard presentation box, with a K&F branded microfiber drawstring bag included. They would make a great gift for a photographer, assuming you know what size filters they use on their lenses.

These are excellent quality filters and are well worth the price, so I highly recommend them.