This adapter can be plugged into a standard optical socket (SPDIF/TOSlink - found on amplifiers, cd players, etc) to create a 3.5 mm optical socket input/output, thus enabling optical cable to be used.. 3.5 mm optical cables are currently used with mini disc players, laptops and many Apple devices. 3.5 mm optical connections are not the same as 3.5 mm analogue audio connections like on many MP3 players.