The 0.23oz (6.4g) mount is designed for bayonet-mount mobile cases (e.g. those by RhinoShield, Moment, and Sirui) — simply align the alignment markings on the mount with the bayonet features on the case and twist it into place. You can then twist any 52mm filter onto the threads.
It’s “the perfect solution for adding ND, CPL and other 52mm filters to iPhone 11 models and numerous other multi-camera iPhone models,” Moondog Labs writes.
If you want to use the mount on a dual- or single-camera iPhone, there are self-adhesive baffles included in the box for blocking stray light.
Here’s a 49-second video that introduces the new mount and shows how it works:
The Moondog Labs Multi-Camera Filter Mount has a price tag of $35 and will start shipping on March 6th, 2020.