Polk Audio RTiA3 High Performance Bookshelf Loudspeaker, 40Hz-27kHz, Pair, Black Neodymium magnet,low-viscosity ferro-fluid cooling,and a heat sink on the back of the magnet, create better power handling and reliability Magnetic shielding for safe placement near video sources Mylar bypass capacitors in the crossovers extend high frequency response and improve detail and transparency Gold-plated 5-way binding post inputs (with wide holes for large-gauge bare wire connections) for the most secure connections and the most versatile wiring applications Floating anti-diffraction grilles minimize grille diffraction for spacious, 3-dimensional imaging