The JBL-MTC-442MR is an optional mud ring bracket used with Control 400 Series ceiling speaker installations in sheetrock or gypsum board applications. It supports pre-install planning by reserving the speaker location before the sheetrock is installed and provides a point to secure wiring behind the surface.

The circular offset forms an edge guide for plastering, helping create a clean finished cutout. Its winged bracket design attaches to the building structure, making it suitable for production-line style ceiling preparation where consistent cutout positioning is needed.