JBL MTC-419MR Ceiling Speaker Mud Ring Bracket for Control 419CS/T (Pack of 6)This optional mud ring bracket is designed to facilitate a specific ceiling speaker installation method in sheetrock before the wallboard is installed. It helps reserve the speaker location, provides a point to secure wiring behind the sheetrock, and supports repeatable layout in production style jobs. The circular offset forms an edge guide for plastering, allowing the sheetrock opening to be finished cleanly up to the ring. Wings attach to the