The Pioneer A Series of Shallow Mount Subwoofers uses a highly rigid cone made with MICA-injected molded resin which creates a rigid and durable cone. This gives it the ability to produce accurate bass. The shallow-mount subwoofer also has multiple, patent-pending features that deliver the big bass performance of a full size subwoofer, but in a compact design that can be installed either behind or under seats, depending on the type of vehicle..