Call Center Headset Headphones + Adjustable Volume + Mute Control For Phone Nortel Networks NT Northern Telecom Meridian PBX M3903 M3904 M3905 M2216 M2008 M2616 3903 3904 3905 Meridian Option M3110 3310 3820 i2002 ip2002 i2004 ip2004 NT8B20 NT8B30 NT8B40 NT8B50 NTZK23AA AB M2216 ACDI Ip Telephone Direct Connect Over The Head Headset, No Additional Applifiers / Adapters Required. Built-In volume adjustable and mute button control. Shirt clip included. Soft Leathered Ear Cushions For All Day Comfort. Superior Quality Sound with the Flexible Adjustable Microphone. Headband Style with Single Earpiece for Great Sound Quality in One Ear.