Plantronics CS540-xd 900Mhz for use in high wireless headset density locations 90 available channels Up to 7 hours of continuous talk time Optional wideband frequency offers a fuller, more robust call quality Customizable fit allows you to wear the headset over-the-head or in-the-ear. Both styles offer an adjustable fit for ultimate comfort Noise-canceling microphone cuts out most background noise 64-bit digitally-encrypted signal. Nobody can listen in on your calls Increase your productivity by answering and ending calls when you're away from your desk with the recommended Plantronics HL10 Automated Handset Lifter (Optional) Easy installation