Convenient In-line Controls: Convenient inline volume and mute controls allows a more flexible listening experience. 5.4ft long cord offers flexibility to move around,designed to keep pace with the demands of work and life. Ultra Durable: Precision design, quality plastics, unibody headband construction, metal mic boom joints makes this call center headset sturdier and more durable. You can even pull or bend the headband for personal optimal fit. Most Comfortable: Super lightweight office telephone RJ headset with adjustable headband to fit all head sizes, high quality and soft leatherette ear cushion enhance all-day wearing comfort. Compete with Plantronics or Jabra heavy duty Phone Headsets for Call Center, Telemarketing & Office. HD Voice for Clear Communication: Wideband Sound telephone headset enables natural listening experience, noise canceling microphone provides greater focus and concentration by blocking background noise, plus acoustic Shock Protection to protect your hearing. Less noise, Clearer voice. SEE COMPATIBLE PHONE LIST IN DESCRIPTION. ?NOT for Cell phones and Computers?Direct connect landline telephone headsets ONLY Compatible with Some Specific Phone Models from ShoreTel Plantronics Zultys Toshiba NEC Aspire Dterm Nortel Norstar Meridian Siemens ROLM Packet8. Compatible with Polycom: SoundPoint 300 301 335 430 450 500 (rev. E or later) 501 550 600 601 650 670 CX300 CX500 CX600 CX700 VVX300 VVX310 VVX400 VVX410 VVX500 VVX600 VVX1500.