*DISCONTINUED* by Plantronics, no replacement
This is a special "Y-cable" made especially to be used with Plantronics busy light (OLI) and the older Plantronics "CS" series wireless headsets (CS50, CS70, CS70N, CS351, CS351N, CS361, CS361N) and EHS cables.
It splits the jack into two ports (one for the EHS cable, one for busy light), allowing the use of both. Without this cable, you can only use one.
Also known as SSP-2605-01