The JBL MTC-42MR is an optional mud-ring (plaster-ring) bracket designed for use with Control 42C ceiling loudspeakers. While most installations require no additional hardware beyond the included mounting system, this accessory simplifies sheetrock and gypsum board installations. It allows pre-installation before drywall is applied, provides a secure point to strap wiring, serves as a cutout template for multiple speakers in production-style projects, and ensures precise speaker placement. The circular offset forms an edge guide for sheetrock plastering, while integrated wings fasten directly to building structures. Once installed, sheetrock can be cut and plastered flush to the ring, producing a seamless finish around the loudspeaker.