http://www.phantomfilters.bigcartel.com/products.

Would u buy this over individual screw on filters? Need these horribly bad for video. Not that big a deal with stills

If it were me then I might think about saving up a bit longer. You have a nice 4k camera, a lens system that is an improvement over the P3. Why spoil the image with cheap optics. It's entirely your choice of course and I am no expert on the camera used on the P4, you could try them and be delighted. But from my other hobby of Astronomy imaging the better path is usually to get the best you can afford. Each time you changed them there would be finger prints on the surfaces.

Great point. I appreciate the response . I think I'm for sure getting dji nd16. I've read from people that the polarized one is a must but the nd4 is fairly useless. Thoughts? Is nd8 necessary?

Depending on the lighting conditions: bright sun really needs an ND16, on overcast days or late afternoon an ND8 is enough. I use only these. You want the shutter speed to  be about double the frame rate (25 fps => 1/50 sec exposure). When shooting photos instead of video don't forget to remove the filter. As for a polarized filter, you've got a fairly wide-angle lens; the polarization varies across that field, so personally not sure that its so useful in this case.

Those filters are nice. Especially as they are stackable.

But, they need to be handled very carefully. It's very easy to get fingerprints on them and they are plastic so more susceptible to scratches than glass filters.

@johnsr 's explanation is spot on regarding ND filter use.

If you want to get a bit more info about making video with your Phantom (ND filters, frame rates and settings) we have an article about that; Making better video with your DJI Phantom 4 / 3 / Inspire

craig.davis.850 Posted at 2016-4-25 00:34
Great point. I appreciate the response . I think I'm for sure getting dji nd16. I've read from peopl ...

Hey Craig,

The ND8 and ND16 are probably the most common filters to get your shutter double the frame rate. We use ND32 and even ND64 sometimes over snow. CP's are good for filming over water, the only problem is they are the equivalent of ND4. So in bright scenes they don't reduce shutter enough, if you shoot with a CP try an ND8/PL or ND16/PL.
Hope that helps!

Jeff

craig.davis.850 Posted at 2016-4-24 23:34
Great point. I appreciate the response . I think I'm for sure getting dji nd16. I've read from people that the polarized one is a must but the nd4 is fairly useless. Thoughts? Is nd8 necessary?

Have you tried a combination of both? Best results are achieved using a ND/POL combo, a solution only possible when using "sanwiched" gel filters