I got the 77mm filter set to go with my new Sigma 17-50mm f2.8 lens. Big filter diameter, so big filters. I don't make it a must to put UV filters on my lenses usually, but the huge front glass element of the 17-50 seemed like it would be prudent to protect, and to just make things easier to wipe off moisture or dust. I haven't made a lot of use of the ND or polarizer yet, but I do need those sometimes, and the three-piece set of UV, ND and Polarizer is the most practical to carry with the camera. I do wish the ND filter were a little stronger than a 2-stop ND4, as when I need one I typically need a little more strength. Most cameras these days have electronic shutter options for faster speeds, but especially if you are showing motion blur, electronic shutters produce unpleasant rolling shutter effects. But I'll take the ND4 and will probably be able to get what I want with some settings rejiggering. Optical quality is good, no complaints. My favorite feature of these is the the easy-to-grip raised edges on the ring. Anyone who has struggled to get a filter unscrewed when it has been tightened and sat on the end of a lens for a while will know exactly what I mean. You'll never have that problem with these.