One side 3.5mm Stereo Male Pin, Other side 6.35mm Female socket
This 3.5mm to 6.35mm stereo adapters allow a standard 3.5mm (1/8 inch) stereo port to accept a stereo cable with a 6.35mm (1/4 inch) plug.
It is widely used to connect your headphones, smartphones, tablets, iPod, MP3, computer or any device with standard 3.5mm 1/8 socket to most sound system-like amplifiers, home theater device, AV receivers, guitar, mixer cords, PA etc