After lots of curves and looking at the end I settled on this square metal filter holder and adapter rings. They are better than I expected and I was surprised by several things: 1. The speed of shipping and the seller's response (Excellent) 2. The presentation and protection of the product. In padded envelopes, properly packaged to avoid damage. 3. The quality of having it in my hands. They look very resistant and fulfill their function perfectly. I definitely recommend your purchase.

Very good quality K & F Concept ND1000 square filter set consisting of glass filter holders and lens adapters for the filter holder. The package is divided into 3 parts: 1. A bag with metal rings adapters for different lens diameters. 2. A case containing the filter and its leather carrying case. 3. A box with the filter holder. The adapter rings allow us to place the filter holder on any lens as we have a large number of different diameters. They are made of black metal and are well made. With inscription on each ring of the corresponding diameter. The filter is made in Germany glass. It is a 100x100mm square and 2mm thick ND1000 filter. It allows us to remove 10 levels of light to make daylight long exposure photos perfect. In the example photo I've hung, midday is taken at around 30 inches. I love the game that you can get to this filter. The filter comes in a leather case and tissue paper. The case is heavy enough to protect it properly. The glass does not mark easily with fingers and does not attract dust. The filter holder is metallic with the part where the filters come from some kind of very hard plastic. They fit easily on two filters 100x100 and also on the slopes 100x150mm. The attachment system on the adapter ring is thanks to a very handy metal tab. In several tests I ran under different lighting conditions, I didn't notice the ingress of residual light because of the space between the filter and the portafilter. The photographs have a slight magenta tint that is very easy to edit, but they are not overdone at all. With the complete kit and price, it's a fantastic filter to experiment with and get excellent results. I'm really excited and really enjoying it. I highly recommend it!

For safe storage of three square filters 100 x 100 mm and a filter holder. The case seems sturdy and looks pretty good.

It's my first square filter set - so far I've only ever worked with screwable round filters. The first thing I noticed was the very classy and practical packaging - the loop for removing the filters from the storage case is ingenious. The scope of the adapter rings is very plentiful. Coupling the filter holder with the adapters is easy. However, pushing in the filter plates is very difficult, so that sometimes I'm even afraid that I could damage my lens. But now I read in the insider tips that you should loosen the built-in screws in this case - I haven't tried that yet. It is also unfavorable that the filter holder cannot be fixed in the axis of rotation - it can be rotated very easily, like a propeller. Nevertheless, I would like to say that the system is fun and delivers very good results (eg no discoloration).

I had been hesitating between several brands for a while to choose a filter holder for ND and GND filters. I took advantage of a flash sale to acquire this kit. I am not disappointed.
the set seems robust and easy to store.
The case, quite pretty, has 5 compartments, 3 of which, for square ND filters, can be lifted by means of a ribbon. On the back of the case, there is a ring to pass a strap and a passage for a belt. I would have liked a slightly more spacious compartment to house the adapter rings with the CPL filter when it is disassembled.
The assembly (or disassembly) of the elements is well explained in a manual in several languages, including French.

Main positives:
No color cast or loss of sharpness on the first tests carried out.
The plastic frame with its tabs to handle the ND filters.
The CPL filter installation system on the filter holder.
the knurled knob for mounting the adapter ring and the rotating block of the filter holder.
The very accessible wheel to control the polarizing filter.
Firm hold of the square filter on the filter holder.
The robustness of the metal filter holder.

If you have to find some negative points:
The slightly too vigorous maintenance of the square filter in the filter holder.
the click too hard to lock the CPL filter in the filter holder.
No pouch to independently protect the CPL filter in the case.
No CPL protective cover when the assembly is installed on the lens.

Very high quality ND1000 K&F Concept square filter set consisting of glass filter, filter holder and lens adapters for the filter holder.

The package is divided into 3 parts:
1. a bag with metal adapter rings for lenses with different diameters.
2. a box with the filter and its leather carrying case.
3. a box with the filter holder.

The adapter rings allow us to put the filter holder on any lens, since we have a large number of different diameters. They are made of black metal and well made. With inscription on each ring of the corresponding diameter.

It is a square filter ND1000 100x100 mm and 2 mm thick. It allows us to remove 10 light levels to make long exposures in daylight perfect. In the example photo I posted, it is taken at noon at 30 ". I love the play that can be taken from this filter.

The filter comes in a leather case and is covered with tissue paper. The case is sturdy enough to protect it properly.
The glass is not easily marked by fingers and does not attract dust.

The filter holder is metallic, with the part where the filters rest being made of some kind of very hard plastic. They easily fit two 100x100 filters

K&F Concept Square Metal 100mm Filter Holder with 8 Lens Filter Adapter Rings 49mm to 82mm. Great addition to my filter collection. I bought the wrong size filters so I had to buy this kit. Well built product with most of the adapters I needed. K&F seems to be making some really good stuff at a great price that will help us amateur snappers without breaking the bank.

In addition to square filters, I also bought the low-cost magnetic filter holder set. I can only say top. However, I lack the possibility of obtaining ND 8 and ND 64 (magnetic) because only ND 1000 and polarization filters are available. A second glass-filled filter holder is included, which is super durable with adapter ring for a second lens size and yet! fits into the super handy case. For the time being, this low-priced set with magnetic holder is enough for me; for further demands, I will probably switch to another manufacturer's “large” filter holder system (about 400 euros with three ND filters). Which photographer doesn't know this “want to have?” In short: Riko Best's contribution to YT convinced me. Would I recommend it? Yes, anyone who wants to work with grey filters now and then. LG