Heyrtz Telephone Headset Rj9 Plug Single Sided for Polycom Soundpoint Ip Phone 501 550 600 Monaural over-the-head wearing style for comfort and awareness of environment Direct connect over the head headset, no additional amplifiers or adapters required 2M coiled wire Telephone Headset Rj9 Plug Flexible boom design allows to adjust mic freely RJ9 connector to replace telephone handset