Klipsch RB-10 Bookshelf Speaker (Pair) Type: Bookshelf Speakers Driver Units: Two way system using one 1 (2.5cm) magnetically shielded, titanium dome compression driver with an integral 4 (10.2cm) square 90 degrees x 60 degrees Tractrix Horn and one 4 (10.2cm) magnetically shielded, Cerametallic cone woofer Power Rating: 50 watts (200 watts peak) Nominal Impedance: 8 Ohms Sensitivity: 90dB @ 2.83 volts/1 meter