Promaster 46mm IRND16X (1.2) HGX Prime

The thin profile of this filter lets me stack it with a circular polarizer without any vignetting on my 24-70mm, and it cleans up shadow color casts perfectly.

The dirt-repelling coating really works—I was shooting in dusty conditions and barely had to clean it. The IR suppression is also noticeable in my long exposures now.

Ground it takes the IR cast out of long-exposure shots completely, and the multicoating sheds salt spray and fingerprints like nothing I've used before. The polish on the glass is obvious the moment you hold it up to a light source.