Recessed faceplates provide for a cleaner more flush installation to give your cabinet a higher-end, more custom look. They fit a wide variety of aquarium controllers, pump controllers, and auto top-off (ATO) controllers.
Some popular examples include:
EcoTech Marine VorTech Pump Controllers
IceCap Gyre Dual Pump Controllers
Reef Octopus VarioS and Octo Pulse controllers
HYDROS line of smart devices - including the WaveEngine, Control 2, and Control 4.
This faceplate occupies two of the eight slots on the Controller Cabinet.