Amazon.com: Cisco Headset 561, Wireless Single On-Ear Digital Enhanced Cordless Telecommunications Headset with Standard Base for US & Canada, Charcoal, 1-Year Limited Liability Warranty (CP-HS-WL-561-S-US=) : Everything Else
Cisco 531 CP-HS-W-531-RJ= Headset Wired Single with Quick Disconnect coiled 889728143745 | eBay
Cisco 531 Corded Mono Headset with QD Coiled RJ Cable for Quick Disconnect
Cisco Headset 500 Series Data Sheet - Cisco
Cisco Headset 500 Series Data Sheet
Cisco 521 Wired Single - headset - CP-HS-W-521-USBC - -