Plantronics Blackwire C435 is a Lync Optimized USB headset whose claim to fame is that it can be converted from stereo to mono by removing the 2nd earpiece.
First of all what is included with the C435? A case, manual, multiple ear gels, and a cap to seal the connector when using the headset in mono configuration.
The manual is basically one page shown below. Its simple to put the headset on: Aim the mic boom at the floor, put in ear, and twist boom to operational position. Part of the ear gel will lock into your ear, avoiding the mic boom from swinging away from your mouth.
The headset is controlled by buttons located on the audio cord. There are two lighted buttons: Mute (red LED) and Pickup/Hangup (Green LED). Up/Down volume is in the center and position is indicated by audio tone.
To convert the headset to mono you just unplug the 2nd ear piece and put the cap on the connector. It is pretty tight when new, but I suspect with use it is less so. The connector is grippy rubber to pull it apart.
Well, that’s all!