I'm really excited about these new filters that K&F are releasing. The magnetic filter system is a great idea for strong ND filters as I often have to compose my shot without the ND filter attached (because without it it's much easier to see through the lens) and then have to attach it to take the shot . Being able to easily snap the filter onto the front of the lens takes a lot of effort out of removing and reattaching the filter.

The optical quality is excellent, with excellent clarity and hardly any color cast. The processing quality of the metal rings is solid; They are smoothly machined with smooth edges and beautiful knurling. The rotating ND filter rotates smoothly, with hard stops at both ends of the spectrum so you'll know when you've reached the limits.

The magnetic attachment keeps the filter firmly in place, but is probably best used in controlled tripod setups where you know the lens won't be bumped. I definitely wouldn't use this in mass situations where someone or something might knock the filter off, as it wouldn't take much of a jab to make that happen.

No lens cap is included, presumably because the extra weight would make the filter too heavy for the magnets to comfortably hold. K&F makes a magnetic lens cap that I got with another K&F filter set, but it doesn't fit on the outside of the ND filter because the outer ring is larger than 77mm. However, the magnetic lens cap fits on the inner ring, so you can use it when you don't use the ND filter. As far as I can tell, you can't buy the magnetic lens cap individually, only in a bundle with other filters.

The quality of this filter is quite comparable to that of Tiffen. It's reasonably priced and I would definitely recommend it for tripod landscape photography.