Do you have a device with a 3.5mm plug that won't fit into your other device with a 2.5mm jack, such as a pair of standard headphones and a new smartphone? If so, you need this adapter from Monoprice!
This adapter has a stereo 3.5 mm female TRS jack and a stereo 2.5 mm male TRS plug. The connectors are gold plated to ensure a smooth, corrosion-free connection.
Important: Although this adapter will physically connect a headset to a smartphone headset/microphone jack, this will not allow use of the microphone. This adapter has TRS (Tip-Ring-Sleeve) connectors with three contact points, while a headphone/mic device requires TRRS (Tip-Ring-Ring-Sleeve) connectors with four contact points.