It sounds like you're describing a customisation option for an EVC Throttle Controller. The EVC Throttle Controller appears to have a default white interface, and users have the option to customise it with a black faceplate. This faceplate is designed to stick over the existing white interface, allowing users to personalise the appearance of their EVC Throttle Controller.

It's important to note that these faceplates are specified as not compatible with evcX Throttle Controller models, indicating that this customisation option is specifically intended for a certain version or model of the EVC Throttle Controller.