In, an Earphone/Microphone stereo jack and includes internal storage as well as MicroSD support. The Sound BlasterX P5 is an earphone with an inline microphone. This can readily be demonstrated by connecting a battery, microphone and earphone in series. If the microphone and earphone are brought in contact the system will oscillate. The Cougar Boy came with a 4-in-one game cartridge and a stereo earphone. Carbon nanotubes have also been applied in the acoustics (such as loudspeaker and earphone). In some sets the earphone cord had enough capacitance that this component could be omitted. The voltage was adjusted with the potentiometer until the sound was loudest in the earphone. Its hardware product line includes the Smartisan smartphone and the Smartisan earphone. The listener connected the improvised earphone to the foxhole radio and received three radio stations. When applied to an earphone this would reproduce the transmitted sound. In a receiver's earphone, this sounded like a musical tone, rasp or buzz. An optional earphone sold for $7.50. These controls were adjusted until the station sounded loudest in the earphone. He acts unflappable and doesn't falter as Britney gives him instructions through a hidden earphone.