Have you considered the Freewell variable ND filters. Very useful, quicker, only $49 USD, can be adjusted between recognized stops. You don’t say what drone this is for, but I’m sure they are available for the M2P and the MM.
Very happy with mine.
Razor Sharp optical glass used to ensure optimal quality aerial images 16Layers multicoated optical glass lens filters ensure crystal clarity in captured footage Super lightweight CNC ring used in construction prevents adverse effect on gimbal Freewell Gear Variable ND Kit includes –2-5...
I have the NISI M1P 6 pce set and they work great.
NCUV, C-PL, and ND 8, 16, 32, 64.
Although they are in general (at least here in Oz) about the same price as PolarPro.
I also bought their Natural Night filter a while ago, but haven’t had an opportunity to try that in ideal circumstances (we can’t fly at night here).