The 2.5mm jack connection is slightly smaller than the standard headphone jack found on Stereos and PCs at 3.5mm. Most commonly the 2.5mm jack is used on small and compact designs such as mini discs and MP3 players to save space.
Gold plated male connectors Strain relief ends 2.5mm stereo socket 2.5mm Stereo jack plug
Please be aware that this is smaller than the standard headphone size which is a 3.5mm connection If you require the standard 3.5mm stereo jack extension please see QS: 00225