The new High Definition Sound (HDS) PPB series is the culmination of Peerless working in close partnership with end users of Peerless-based audio products. With a deep understanding of customer requirements and needs, Peerless developed the proprietary and highly advanced Polypropylene Black (PPB) cone material used in the HDS PPB Series, creating a stiff but still dampened cone that remains stable even under the greatest sound pressures.