Cellet CNY3TO2BK 2.5mm Male Input to 3.5mm Female Input Adapter with On/Off Switch and Microphone for Cellphones - Retail Packaging, Black 2.5 mm pin to 3.5 mm hole adapter Use your favorite pair of 3.5 mm headphones to listen to music Universal 3.5 mm standard headphone jack Not recommended for cordless and office phones