Good building quality and good underexposure :)
The Sandmarc Motion Variable Filter is built really well and does the job of a very high priced ND filter on a DSLR without altering any color on your video. i highly recommend this product for mobile phone video capture
If only phones had an aperture diaphragm! This lens would be absolutely perfect but due to phones adaptation to light on the software level, it’s not as affective as I’d hoped. I try pushing my iPhone 12 Pro Max to do what my DSLR can do but you can’t fit a round peg into a square hole. This product works best under already low light conditions but not for daytime water motion effects. The image provided was under quite a bit of shade. It’s okay, but I’m picky and like longer exposure. Not the fault of Sandmarc guys, it’s the phone makers. This is why I still hang onto my DSLR, more flexibility. The filter does work well for video as intended.
Only thing I can complain is the cover, it could be made to fit the lens with the mount properly and safely