To keep shutter speeds at the desirable speed we inevitably need ND filters. So what do you put on your $1500 drone? "You spent $1500 on your drone, so why would you want to go cheap on your filters?" some would say. A good point. And so I looked at the PolarPro brand which were double the cost of the Skyreat brand. As a professional photographer I know how to check for quality in filters: 1) Consistency across the image. 2) Color shift. 3) Accuracy of light reduction. 4) Ease of installation. 5) Storage in transit.I'll address one of the objections I heard from reviewers, ease of installation. I have absolutely no problem at all installing these filters. Once the Hasseblad filter is off, the four prongs fit perfectly into the holes and a small clock-wise twist secures them well. No issues at all. So that leaves the other categories.Color shift: This is digital. We have to set a white balance somehow. Who is to say your camera is perfect? Are you calibrating it or calibrating the images and creating a profile? Are you setting the WB to the finest degree possible? Is your monitor high quality and calibrated. Would perfectly neutral ND filters give you a perfect picture? I cannot detect a color shift because I am not confident that I've got the other ducks perfectly in a row, but I know I can color correct to the point where I like it (to the best of my skill's abilities). My uncertainty is the only reason I didn't give it 5 stars at this time. Once I use them more I may come back and revise my rating and review.While I haven't put the filters under the "acid test", to the best of my ability I see no variation of exposure across the images. It would stand to reason because my measurements tell me that the light reduction is within 1/10th of a stop across the board. I measured each of the ND filters (not the polarized ones) with my calibrated Minolta FlashMeter V with its flat disk incident dome. You can see from the photos attached that the actual filtration is very close to perfect as rated. Again... see attached photo with readings to 0.1 stopsA minor detail but good to have, is the case these filters come in. The filters sit securely in their foam cut-outs. They won't slide around in their case and possibly get scratched up in travel. They come with a cleaning cloth that fits in the case, so you can give them a quick wipe before installing them without taking them out of the case or searching for a cloth. The packaging was well thought out, not too thick and not too thin. Fits well in the lid of my case.Conclusion: I could have spent 2x the money on the Polarpro filters and it wouldn't have changed my lifestyle. Would they have been better than the Skyreat? If better at all, not 2x better. IMO there isn't enough difference to warrant that much extra money. If they were $10 or even $20 more, I would have purchased the Polarpro brand. Perhaps one day I will get them for a side-by-side comparison.