The Tractrix horn in the PL12 provides a spherical wave-front transition from throat to mouth (like the bell of a trumpet) for smooth high frequency response up to 60 degrees off axis. The 1" RCF HF mylar driver provides crystal clear highs usually associated with more expensive systems. Specially designed Eminence 'M' roll surround woofers with convex dust caps for increased efficiency and clarity give these boxes a big sound. The PL12 has been known to outperform many single 15" two way systems. PM10/12 Enclosures are wedge style floor monitor versions of the PL10 and PL12.