Promaster 升級環 - 40.5mm-52mm

Fits perfectly and the threading is smooth as butter—no annoying grinding or cross-threading like with cheaper rings. Used it to mount a 52mm filter on a 40.5mm lens and it hasn't budged.

Finally a step-up ring that doesn't cross-thread or feel flimsy—the precision machining is noticeable when screwing it on. It's thin enough that my lens hood still fits afterward.

Fits my 40.5mm lens perfectly to use my larger 52mm filters, and the metal feels solidly machined without any wobble. A simple solution that does exactly what it should.