CQtransceiver Comfortable Landline Wired Telephone Mono Headset RJ9 Connector for MITEL Superset 4000 4015 4025 4125 4150 Telephone Direct connect over the head headset, no additional amplifiers or adapters required 2M coiled wire Flexible boom design allows to adjust mic freely RJ9 connector to replace telephone handset Monaural over-the-head wearing style for comfort and awareness of environment