The Plantronics A10 inline corded amplifier is a simple, plug and play adaptor ideal for connecting all Plantronics corded headset styles to compatible telephones. It is a dedicated adaptor, so there are no controls or switches to set or change, and it uses Plantronics Quick Disconnect to allow a choice of headset. The Plantronics A10 Direct-Connect headset cable is for call centers that use both Plantronics Polaris brand headsets and amplified headset solutions like the M12 or M22 Vista combined with any h-series headset (e.g. H251).