What this controller is and what the sampling speed buys you
The Fuji Electric PXF4ACA2-FVJA1 is a self-tuning 1/16 DIN (48 x 48mm) compact temperature and process controller with a 50ms sampling speed. The self-tuning algorithm handles initial setup; you still want to verify the response on a process upset, but it gets you close out of the box.
The 1/16 DIN (48 x 48mm) cutout is the standard small-panel footprint — fits the same hole as every other 1/16 DIN controller on the market, so a swap-in replacement doesn't require re-punching the panel. No DIN-rail mount on this form factor; it's a panel-mount with a gasket seal. If your enclosure sees washdown, verify the front-panel IP rating against your spray pressure — the controller body itself is not rated for submersion.