Monoprice 107122 2.5mm Mono Plug to 3.5mm Stereo Jack Adaptor,  (3 Pack) 2. 5mm Mono Plug (male) to 3. 5mm Stereo Jack (female) Adaptor - Will fit smartphone headsets however it will not support the speaker or mic functions on the headset. Save when you buy the 3-Pack! - It is a reliable and efficient product for you