Ive purchased the Polarpro Shutter Cinema ND filter series already (which includes a ND 16, 32, and 34 filter) and love the quality it gives my film. I am having an issue trying to get my shutter speed right when dusk is setting in though and was looking at purchasing a ND 4 filter.
Is there a large need for a ND 4 filter?

I wanted something lower than a 16 ND when the sun is setting,  but it appears with Polarpro, I can only purchase the VIVID series which are all polarized...... Not sure if this is the direction I need to go...... Guess I'm just looking for some direction.

It looks like you have that need right?
On overcast days that might be the one you need to get to the best shutterspeed.
Not sure about the P4, but you can't change the aperture right?

Hi James,

We'd be happy to provide some additional insight here.  The ND4 is definitely the recommended filter to use in sunrise/sunset situations, where the available light will typically be too minimal to allow for the use of an ND8 or higher.  If you're only looking for the one filter rather than a set, and it's not listed individually on our site, please reach out to our customer support team at support@polarpro.com and we'll be happy to get a custom order set up for you.  We can also answer any other questions you may have about the filters.

- Oliver from PolarPro

I use a ND4 in early morning / overcast days.   Most other times I use either a ND8 or ND16  from the Polar Pro Vivid Set.

180-degree shutter on the P4 isn't significant enough to bother using ND4 for golden hour situations. Too much hassle for no noticeable improvement to footage. Test it yourself and you'll agree! Have fun out there.