JL Audio Mounting Adaptor Plate f/MediaMaster MM50/MMR-40 - MMP-2-BK [010-13860-00]Mounting Adaptor Plate for MediaMaster MM50 MMR 40 MMP 2 BK The MMP 2 BK mounting adaptor plate allows you to install a MediaMaster MM55, MM50, or MMR 40 into existing source unit openings that are larger than needed (up to 8. 17 x 3 inch 208 x 80 mm). Constructed from a single piece of marine grade, machined aluminum, the MMP 2 BK provides a solid surface to mount your MediaMaster MM55, MM50, or MMR 40 in locations previously occupied by other marine