Well, how timely!! I just went through this in a thread that carried out over the several days last Thursday and Friday I believe.
The crux of the matter is that I ordered two Freewell filters for my nw
Mini 2 and tried for over an hour to get them to attach and stay on...all, to no avail. On one trial, the filter got caught behind the camera and took me great effort with a jewelers forceps to retrieve it. The filters fell off continuously as I hovered the drone at eye level in my driveway. I was certain that if I went higher, I would lose it forever.
Once I got it to stay on, but the minute I put on the gimbal guard it fell off.
I returned the filters to Amazon and got immediate credit back to my credit card. I wrote to Freewell and got a total denial reply, stating that they had sold hundreds or more of these without a problem. I have now ordered a single ND16 Skyreat which is coming soon so I cannot vouch for it. The Skyreat is plastic whereas the Freewell was glass. Since this is only a backup drone, I am not going to stress over it.