I have recorded this short video to demonstrate how easy is to setup a NiSi V5 Holder with CPL and ND/GND filters.
This system is the best I have tested so far, because not only is easy to mount, but it features an integrated CPL which is located just in front of the lens and before any other filter. This will reduce vignette and will simplify the adjustment of the polarization angle thanks to the dedicated dial.
NiSi V5 Holder is also really nice and solid. Compared to other holders I tested its borders are wide enough to cover most of other brands filters gaskets: some holders are not that wide and with some ND filters, their gasket is not thick enough to avoid light leaks.
On the market there is no equivalent offer: included in the nice leather box, you will not only the holder with 3 slots and the dedicated circular polarizer, but also a series of adaptor which will let you fit the holder on most commons lens threads.
I would absolutely advice to buy this holder.
P.S.: sorry for my poor English!
Lee, NiSi And Haida Neutral Density Filters: Tests On Color Cast, Calibration And Vignetting