While most mobile devices use the standard, 3.5 mm stereo headphone output, most home audio systems with an amplifier or receiver use RCA jacks for audio inputs. This cable is recommended for connecting the output of an mp3 player or phone to a home audio system. It is made of heavy-duty coaxial cable for each conductor. The conductors are 22AWG and each conductor is shielded to prevent EMI or RFI interference from entering an audio system. A/V Cable, 3.5 mm M/F Ext Cble, Blk, 20ft