JBL MTC-426MR Ceiling Speaker Mud Ring BracketThe JBL MTC 426MR is an optional mud ring bracket used for ceiling speaker pre installation in sheetrock applications. It helps establish the speaker opening before the wallboard is installed and supports a cleaner drywall finishing process. The circular offset forms an edge guide for plastering, while the bracket wings attach to the building structure. In installations where multiple openings are prepared in advance, it also assists with consistent