This 4-conductor 2.5 male to 3.5mm female TRRS converter cable is perfect to convert your 3.5mm headphones or audio extension cable into a 2.5mm pin, for use with phones and MP3 players that have a standard 2.5mm jack. This adaptor is perfect for listening to MP3 with your own earphones, speakers etc. 2.5 mm output allows you to use your existing Kyocera, LG, Motorola, and Sanyo headphones with any CD player, MP3 players, and other audio socket