I have now used the magnetic holder with ND filter several times and am overall very satisfied. Positive: - The fit is excellent; the holder sits securely on the iPhone and does not slip. - The quality of the filter makes a very good impression. I didn't notice any degradation in image quality, even though I'm not a professional analyzing every detail. - The ND filter can be adjusted continuously so that you can adjust the desired darkening very flexibly. - In combination with an app that allows manual exposure, I was able to take impressive long exposures in daylight, for example to beautifully blur running water. - Very practical: The holder and filter come in a sturdy bag that provides protection when you're on the go. Negative: - Unfortunately, the bag smells extremely strong of chemicals. Even after prolonged ventilation, the smell has barely improved. - To use the holder, the iPhone case must be removed. Not a problem for me personally, but could be annoying for others. Overall, a well-thought-out and high-quality set that opens up great creative options for iPhone photography. Apart from the strong smell of the bag (which will hopefully disappear at some point), I am absolutely satisfied and can recommend it.