4Call K500KMC Monaural Call Center Telephone Headset headphone with Mic for Yealink SIP-T19P T20P T21P T22P T26P T28P T32G T41P T38G T42G T46G T48G and Huawei ET325 ET525 IP Phones WORKS ONLY FOR SOME SPECIFIC PHONES, BUY ONLY WHEN YOU HAVE ONE OF THE PHONES LISTED BELOW IN DESCRIPTION Direct connect headset, no additional amplifier or adapter required. Adjustable fit headband and comfortable ear cushions enhance for wearing comfort, even for long periods. Single earpiece with noise canceling microphone for superior sound pick up even in noisy offices. The single earpiece means you can still confer with colleagues while you're wearing it Flexible microphone boom, 270 degree rotatable, which adjusts to suit your preference, you can also choose to wear the microphone on either your right or left side. Long coiled cord stays out of your way by stretching for long reach, and coiling up for regular use. Shirt clip keeps the weight of the cord off your head while you talk, and lets the headset hang freely when you take it off.