3.5mm (1/8") Stereo Male to Male Barrel Adapter. If you need to connect two 3.5mm (1/8") stereo female devices together, you will need to use an adapter or coupler. This male to male adapter plugs into a female stereo connection on each end. It easily inserts into any headphone or 3.5mm socket and provides a stereo connection. Made of high quality metals for maximum audio clarity, and unrivaled shielding protection and against electromagnetic interference.