Sennheiser Bluetooth Stereo Headphones with Microphone MB 660 MS with Active Noise Canceling - Global Teck
Sennheiser MB 660 UC - Dual-Ear Headset with Noise-Canceling Microphone - Includes USB Bluetooth Dongle | Headphone Reviews and Discussion - Head-Fi.org
Manual Sennheiser MB 660 (page 15 of 37) (English)