The K&F Concept Magnetic Variable ND Filter offers a convenient way to control light for smartphone photography. While it has some strengths, it also comes with a few limitations.

Key Features:

Magnetic Convenience: The magnetic attachment system makes it quick and easy to apply and remove the filter.
Variable ND Range: The ND2-32 filter provides a decent range of light reduction for various shooting conditions.
Phone Compatibility: Designed to work with popular iPhone models, offering versatility for smartphone photographers.
Room for Improvement:

Image Quality Concerns: Some users have reported noticeable image quality issues, such as color shifts or vignetting, especially at the filter's extremes.
Filter Thickness: The filter adds bulk to your phone setup, which can be inconvenient for some users.

Overall:

The K&F Concept Magnetic Variable ND Filter is a decent option for smartphone photographers looking to experiment with light control. While the magnetic system is convenient, the potential image quality issues and added bulk prevent it from earning a full five-star rating. If you're willing to accept these limitations, the filter can be a useful tool for your mobile photography kit.