A cassette matrix having a first cassette and a second cassette disposed immediately adjacent to each other is provided. The outer sides of the cassettes are in contact and there are no fastener components, such as, but not limited to, a bolt head or nut, disposed between adjacent sidewalls. In this configuration, the cassette matrix requires a reduced amount of space within a larger housing assembly. Each cassette utilizes threshold mounting fasteners to coupled any components to the lateral sidewall. A threshold mounting fastener does not extend outwardly beyond the general plane of the lateral sidewall.