10pcs 3.5mm 1/8" Male Stereo to 2.5mm Female Jack Audio Adapter Converter Nickel. 10pcs Gold Plated 2.5mm Male Plug to 3.5mm Female Stereo Audio Adapter Converter. 10pcs Gold Plated 3.5mm Male Plug to 2.5mm Female Stereo Audio Adapter Converter.
eBay