The Street Fighter 4 Action Command Voice Keychain, or cell phone strap, are limited to just 1,000-units of each character (Ryu, Dhalsim, Ken and Chun-Li). Just like the actual game, you perform special moves with the joystick and buttons to hear authentic sound effects. Video after the break.
A half circle followed by pressing the “P”-button, for example, will let you hear Ken’s or Ryu’s famous “Hadouken” line. The same command executed on the Dhalsim strap will result in a voice sample saying “Yoga Fire”.