Just from looking at Amazon, Neewer has SEVERAL versions of MP1 filters out there. I have a version that has worked well, but I don't really like how they mount. There is a strip of foam around the inside that provides the friction pressure to keep it on, but it also has a tendency to bunch when installing. I tried the newest version I could find out there, and they have aluminum strips on the inside that work better (more like PolarPro), but the glass was cheaper and they seem to be more poorly assembled. One of them had a noticeable defect that distorted the image. If you want to be sure, spend the money for the better stuff - but if you want to try them, just buy them somewhere with a good return policy.
By the way, after the defective Neewer set, I bought a Freewell set - and the version I got of those used the foam strips too and are harder to install. I haven't found the perfect solution other than spending the money on PolarPro. (I have a few PolarPro filters that I got from BB, but not a full set - and they are great).
My two cents.
LP