This is the Plantronics A10-12 Cable (part# 66267-01) and is the same cable as the regular Plantronics A10 cable, except it has 6dB higher transmit. If you have a direct connect office phone (i.e. Nortel) and needs higher volume, you can use this cable instead. Low volume is a common problem with certain model Nortel Phones (for example, Nortel). This Plantronics A10-12 cable is designed for use in Europe, Australia and New Zealand, and may cause an echo if used on phones in North America.
Note: Use this cable only if your direct connect headset volume is too low. It may cause distortion or echo if your phone already have enough volume.