Signature Series styling with a cast aluminum frame, aluminum cone, and rubber surround visually identical to the SS12-22 driver. The passive radiator design delivers deep bass extension from compact enclosures while avoiding port noise. The Sandwich Mass Structure (SMS) places added mass between the spider and surround for improved stability and symmetry. Simple tuning is achieved with a threaded bolt, wing nut, and nylock nut, ensuring secure mass adjustment. It includes five 116 g weights for flexible tuning options. An ideal companion for the SS12-22 in compact high-output systems