I'd been debating between several brands for a while when choosing a filter holder for ND and GND filters. I took advantage of a flash sale to purchase this kit. I'm not disappointed.
The whole thing seems sturdy and easy to store.
The case, quite attractive, has five compartments, three of which, for square ND filters, are lifted by a ribbon. On the back of the case, there's a loop for a strap and a belt loop. I would have liked a slightly more spacious compartment to accommodate the adapter rings with the CPL filter when it's removed.
The assembly (or disassembly) of the components is well explained in instructions in several languages, including French.

Main positive points:
No color cast or loss of sharpness on the first tests.
The plastic frame with its tabs for handling the ND filters.
The system for attaching the CPL filter to the filter holder. The knurled knob for mounting the adapter ring and rotating the filter holder.
The easily accessible knob for controlling the polarizing filter.
The square filter is firmly held in the filter holder.
The robustness of the metal filter holder.

If there are any slight negatives:
The square filter is held a little too firmly in the filter holder.
The click is too strong to lock the CPL filter into the filter holder.
No pouch to independently protect the CPL filter in the case.
No protective cover for the CPL filter when the assembly is installed on the lens.