""Measured"" color shifts and ND values using a gray card, LR and flash:

ND4: effectively -1.7 stops, shift of +300K towards warm and a decent magenta color cast (LR -12 towards cyan).

ND8: effective -2.8 f-stops, slight shift of -100K to cold and a slightly tighter magenta cast (LR -17 towards cyan)

ND64: effective -5.9 f-stops, decent shift of -500K to cold, but hardly any cyan/magenta shifts measurable.

ND1000: exactly -10 f-stops. Reasonable shift from -200 to cold and hardly any cyan/magenta shift.

Am very happy with the results and you can still easily correct all these shifts. If you want to work with flash + ambient light and these filters, you should pay some attention to the respective shifts and adjust the flash with gels if necessary. The ND values are also very good to perfect. The sharpness of the lens remains very good (even stacked with three filters).

The workmanship is also great for the price (the threads scratch a bit when screwing), but consider the price. Very good entry into the ND world and new even higher quality filters are not necessary in the near future.

The transport bag also makes a very good and valuable impression. Usual China smell, nothing special more in 2022...."