I purchased the K&F X-PRO Square system. I've used other filter "systems" and most work as expected. These filters fit for all of my Nikon lens filter of diameter up to 77mm (or actually 95mm on the mount). The material and construction is exceptionally well manufactured and well thought out in its design. The included manual is clear and well written for we English speaking/written folks at least. The adapting rings offer "just enough" purchase for screw mount to the lens, so be patience and carefully on the mounting them... could use a few more threads, I suppose. Mounting the 95mm polarizing (CP) is a snap - insuring you position the proper direction. Of course, you have two different ways to rotate the CP - using the handy knurled thumb wheel or to lighten the locking the full frame and/or from the full frame assemble.

Now, since I did not give you ALL of this products 5-stars for a silly reason. The package and the "Storage Case" is over killing! Beautifully packaged, thoughtfully planned for the full system with space for growth. I/most have their own storage and transport camera cases(s) and most do not fill this beautiful storage case! I would rather have had another filter or a more spartan case for individual filter cases for my camera bag... as a trade for the case! For me, I found another small & padded case, for my new K&F bracket + the CP perfectly for my camera bag. AND I had hoped that the K&F offered properly protected for individual square lens w/frame separately purchased - but not with success.

SO - it's not Perfect for my needs - though almost! Although this is my "first K&F product, I strongly recommend based on my first purchase!

Greg Wilder