Plantronics 45647-04 Convertible Over the Head / Ear Headset Single Earpiece Easy Hands-Free Conversation Noise-Canceling Microphone Integrated Clothing Clip RJ11 Modular Jack **Plantronics 45647-04 is a Replacement Headset & Will Not Work Without the Plantronics T10, T20, T50, S10 or S50**