As an amateur photographer, I'm thrilled: I can finally use a variable ND filter on the iPhone, as I already know it from my SLR cameras. Although the shutter speed on the iPhone cannot be set manually as precisely as with a DSLR, the ND filter visibly extends the exposure — making the photos look more natural and often even more detailed than without a filter. I find it particularly brilliant that the filter has a classic 67mm thread. This means that it not only fits the iPhone via the magnetic holder, but also to my DSLR lenses. This allows me to use existing filters for both systems — a real link between smartphone and DSLR photography. The MagSafe mount securely holds the filter to my case. Despite the edge of the case, there are no problems with shading in the image. This allows me to install and remove the filter quickly without despairing of fumbling. As I already know it from the camera sector from K&F Concept: Although a Chinese manufacturer, they deliver very good workmanship that is in no way inferior to established brands — and at a fair price. Positive: • Variable ND2—32 filter for flexible exposure control • 67mm thread — can also be used with DSLR lenses • Sturdy MagSafe mount, no wobbling or slipping • Clean workmanship, good image quality • Impressive price/performance ratio Negative: • iPhone exposure control limited, effect not always usable to the maximum (but is due to Apple and not to the filter!) Conclusion: A top tool for photographers who want to combine smartphone and DSLR photography. It's fun, visibly enhances images and brings flexibility to the setup.