2.5mm Headset, Coodio 2.5mm Headphone [Volume Control] [Call Center] Telephone Headset [Noise Cancelling] [Protein Earmuff] Monaural Headphone With Mic Microphone For Office DECT Phone - HS5 Hands-free, protein earmuff provide all day comfort. Boom-style noise cancelling microphone adjustable for optimum level Reversible for use with either ear, comfortable, lightweight design Excellent for use with Call Center Service, Telephone Counseling Services, Insurance, Hospitals, Banks, Telecom Operators, Enterprises Compatible with most basic and business phones such as Polycom, Cisco Linksys, Cisco SPA, Panasonic, Zultys, AT&T, Aastra, GrandStream and many other cordless DECT phones or Cell Phones with 2.5mm headphone jack.