Headset Headphones with Volume+Mute Control+Standard 2.5mm Plug Jack for Cisco SPA Series Spa303 Spa504g and Other, Polycom Soundpoint IP 320 330, Grandstream, Linksys, Panasonic, Cortelco Built-In Adjustable Volume + Mute Control Soft Leathered Ear Cushion For All Day Comfort Superior Quality Sound with Flexible Adjustable Microphone FREE Extra Leathered Ear Cushion Cover, Shirt Clip Include. NO quick disconnect cable, one direct connect only. NOT all 2.5mm plug work, please see compatible list below Please see COMPATIBLE telephone list in description below. NO quick disconnect cable