For Corded phone, 0.9 oz, Mic: Built-in, Mono The Plantronics CS50 headset brings the ultimate in mobility and hands-free conversations to your office phone. Totally wireless, the CS50 gives you up to eight hours talk time and the wireless convenience to roam up to 300 feet while having secure conversations. Compatible with typical office or PBX-based phones, the CS50 headset can be worn on either ear or over-the-head for maximum, long wearing comfort.