21 pc speaker system stereo pc speaker series logitech z colour black transmission mode cable analogue input 35mm jack input line in analogue outputs 35mm phone jack power rating 7 watt frequency response 65 20000 hz speaker system 21 system system active power supply mains connection nominal impedance 4 ohm suitable for smartphone mp3 player tv tablet game console desktop pc blu ray player notebook audio system cdmp3 player speaker contr