They are great!
The quality and price is great... only thing I don’t like is the clip to hold the filter on as it covers part of the screen.. I use it on the XR and you have to place the filter in a specific spot to stop any light from bleeding in from the back side of the filter so it won’t cause reflections from inside the filter.
The lenses work nicely and are fairly easy to switch out as needed. They have performed very well. The clip attaches well, even with a case on my phone. What didn't seem to get the same attention to design was the case for the lenses. It's a safe way to transport them and see all of them at once. The case even has a space for an additional lens. But it's bulky (117 x 117 x 15 mm) in contrast to my phone and takes up more space than seems necessary for people who are already working with smaller equipment. There is also no consideration for the storing the clip with the lens.
Great filters and easy to carry in a small gear bag with tabletop tripod and smartphone mount. Good quality glass. The sales process was exceptional and the good arrived very quickly.
Once I put on your ND16 filter on my iPhone/osmo combo I noticed right away that I was able to drop my iso to 100. That made my picture look so good! Also, noticed right away the build quality of the filters were perfect.