Replacement Handset for 4000 Series Phones. Our handsets are tested to ensure that they consistently meet original Style specifications. The handsets have a noise reduction feature (noise reducing-not noise canceling), are hearing aid compatible and meet static voltage testing. The colors of our handsets are matched to s most recent handset colors. These handsets are brand new (not refurbished), new guts, new plastic... new everything. The handsets are designed to work on the systems listed, but they may function on other systems not listed. If you put it on other systems, use at your own risk.