The James Loudspeaker 540SAS-4 is an in-wall subwoofer designed to be concealed from view. Like all speakers in the SA series, a small opening in the wall or ceiling is the only visible portion of the speaker giving this product series its name, Small Aperture®. The 3.4 inch depth allows the speaker to be placed within 2x4 inch studded walls and concealed by drywall, while the 4.125 inch square grille is the only visible portion of the speaker. The 540SAS-4 is built using aircraft-grade aluminum and has a half-inch thick back plate to ensure maximum durability and limit rearward sound transmission. The speaker comes with bracket mounts to secure the frame to wall studs and ensure that it is firmly locked in place.