The construction quality is very good, you can tell that it is a brand that knows what it does in photographic accessories, at the level of other brands that until not so long ago were leading the way. The magnetic system works very well, the adapter is attached to the iPhone's camera module using MagSafe with a fairly strong connection that doesn't feel like it's going to come loose. The best thing is that you can use it with the cover on, you don't have to take it off every time you want to use the filter. The design has specific cuts for the flash and antenna so it doesn't cover anything or interfere with the phone's signal, this is important because other adapters I've seen don't take it into account. The included 58mm CPL filter is polarizing and works very well to reduce glare and reflections on surfaces such as water, glass or windows. I have tried taking pictures in the pool these days and the difference is remarkable, the colors of the sky are also more saturated and defined. The filter is screwed into the adapter so you can change it for others of the same size if you want to try different effects, K&F sells ND and combined filters that are compatible. The pack comes quite complete with a hard case to store everything, a cord to carry it hanging and cleaning cloths for the glass. The overall feel is of a premium product, both the adapter and the filter have good finishes and feel solid in the hand. The filter covers all three cameras without problems and I haven't noticed vignetting or loss of quality in the photos.