This product is either discontinued or we cannot get that from suppliers.
Poly Plantronics Adapter 18709-01, Two-prong adapter, Compatible with Plantronics Supra, Supra NC, StarSet II and Mirage, RJ-9 jack equipped telephone.
The Poly/Plantronics Plug Amplifier Adaptor Modular is a two-prong adapter will make your modular plug headset compatible with a jack-equipped telephone. This is fully compatible with Supra, Supra NC, StarSet II and Mirage.