People have claimed you can't put the lens cap on this. For the 49mm at least my OEM canon lens cap went on just fine.

It JUST fitted under my glare shield but I can't remove the shield without taking off the filter first.

I can still access all the functional parts though as things like CPL and ND are only really ever changed in a gradual manner on a fixed tripod so I wouldn't ever need to rapidly change it and thus don't need super easy access, but without the shield on this is very easy to quickly adjust.

Worth every penny for what combines about 5 potential different filters into one unit. Very happy as always with K&F

I've been using many K&F filters in the past and I have no issue with their filter.
This one is also perfect for 49mm lens. UV filter I use is to protect the lens, and this does good job.
No image distortion has been noticed.
Highly recommend for good lens protection.

The K&F Concept 49mm MC UV Lens Protection Filter is well made and easy to use. Feels lightweight but great quality. It’s a great product.

The 49mm ND filter came in a typical filter case along with three pieces of microfiber cloth.

The filter looks well made. Clear markings on the filter and so easy to rotate and set it to the desired setting. It is easy to mount the filter onto the lens and remove it. The lens cap fits over the filter just fine.

I shot quite a few images, the light gathered by the lens is reduced as the filter ring is rotated to a higher stop. Happy with the results for occasional use. I can use this filter for long exposure to get say motion blur. My initial review with some shots of the trees showing the light reduction got rejected and so not including them this time.

Perfect fit and lastsI have now replaced all original lens caps from 49mm to 67mm with these. Attaching and removing the lens caps with the lens hood attached is quite fiddly. Often you don't just have the feeling that the lid jumps off right away ;-). There's only a slight difference between the 'original' and this one offered here. I was able to remedy the situation by 'dremelting' a groove in the gripping surfaces of the locking slide the 'original' was too bad for me at first, but there are other reasons for this product: a) the front cover is flat, so that even larger lenses stand securely for a lens change while the back cover is removed. b) the opening for the included safety loop has no opening towards the lens, as with other models.

For beginners, the price is unbelievable and you also get a lens hood that costs more from Canon's original than this whole set would take in its place immediately

I'm really happy that this filter can be screwed onto my Nikkor Z 24-70 f/4 S with the lens hood in place. Obviously I need to reach into the lens hood to adjust the filter, but that's ok. No vignetting that I can see.
The filter works great, nice smooth action and a great range of density.

Works very well, I only recommend buying an additional lens hood because if there is backlight in the picture, it looks purple in the picture. Nevertheless, I am very satisfied, it does what it is supposed to do, I can't complain