S12 AMP W/FIREFLY For the small office and home office, the S12 is stylishly designed for easy use with a choice of headset wearing styles. The headset can be worn over the head for stability or over the ear for convenience. The headset also features Firefly, the in-use indicator light that lets others know you're on the phone. Improve your productivity - filing, using e-mail, taking notes while on the phone. Keep your hands free to multitask. Noise-Canceling Microphone delivers crystal clear voice quality and eliminates annoying background noise. Enjoy the whole conversation. No more unintended interruptions, thanks to the unique boom-mounted flashing red light that lets others know you're on the phone.