Amazon.com: Mobi Lock 3.5mm Plug to 6.35mm Socket (Pack of 2) 1/8 to 1/4 inch Stereo Audio Jack Adapter | Connects Devices with 3.5mm Port to Your Amplifiers, Guitar, Piano, Speakers &
Stereo plastic male 6.3 mm Jack plug, for 6.2 mm diameter cable
Jack adapter for musical instruments and microphone | Ekon
Neutrik Jack Socket 6.3mm Stereo Switched PCB NMJ6HFD2 PennElcomOnline.com