Scandyna The Dock Pack Docking Speaker System for iPod (Black) Frequency: -6dB at 55hz and 25hz. Sensitivity: 93 dB spl (2.83v at 1m) 8 Ohm. Compatible with amplifiers from 10W - 200W output, 8 Ohm Drive Units: One 125mm (5 inch) 4 layer long throw bass/midrange feat. Kevlar piston and 25mm (1 inch) diameter free-mounted high frequency Suitable uses: Center Channel Speaker, stereo arrangement, AV, 5.1, multimedia