I'd heard of K&F concept before and first tried one of their circular polarizers. I went out and shot some sample photos with it to compare with my expensive filters, which I apparently cannot name, because my review of the C-PL in which I named them was rejected. Let me say here that the K&F C-PL impressed me. I thought the shots with my other polarizers that cost four and five times more than the K&F were the K&F shots, because they weren't as good. But I was wrong; the K&F shots were the best. I didn't take these NDs out for comparison, but I did use them to shoot the recent annular eclipse. I got some great shots using the ten-stop filter. No glare, no flare. Since I was bracketing my exposures, and since I had plenty of time, I tried stacking two NDs, the 1000 with the 64, and got a fair amount of flare. I'm not surprised, and I don't hold it against the filters. I know better than to stack them and I'd never do that in any other situation. With either the ND1000 or the ND64 mounted I had no flare. I bracketed exposure to get a decent foreground in some shots and a decent crescent sun on others to later combine in post processing. When I bumped up the exposure for the foreground, the sharpness and color were perfect -- you'd never know there was an ND filter in front of the lens. I expected there to be at least a slight color cast, but there was none. A cast wouldn't bother me, as I shoot RAW and process my own photos anyway, and this is exceedingly easy to correct. The cost of an ND, right? Nope. Not with these. I wholeheartedly and without reservation recommend these K&F ND filters. While I'm at it, I even more strongly recommend the K&F Nano-X series C-PL, a circular polarizer that outperforms my others that cost 4-5 times more.