The JL Audio MMP-2-BK Mounting Adaptor Plate allows for easy installation of MediaMaster MM55, MM50, or MMR-40 source units into larger openings (up to 8.17 x 3 inches). Made from marine-grade, machined aluminum, it provides a solid mounting surface and ensures a secure, watertight fit with its black anodized finish, stainless-steel hardware, and full-surface gasket. The panel mounting holes are countersunk for a clean, unobtrusive look. UV & corrosion-resistant black anodized finish Includes stainless-steel hardware & watertight gasket Countersunk mounting holes for a clean installation | JL Audio Mounting Adaptor Plate f/ MediaMaster MM50/MMR-40 in Black