Klipsch Bookshelf Loudspeakers System RB-61 - Pair (Black) Nominal Impedance - 8 Ohms Compatible High Frequency Drivers - 1 (2.54cm) Titanium Diaphragm Compression Driver Mated To 90x60 Square Tractrix Horn High Freq Crossover - 2000hz Low Frequency Drivers - 6.5 (16.5cm) Cerametallic Cone Woofer Enclosure Type - Bass-Reflex Via Front-Firing Port