Jabra Pro 935 (part number is 935-15-503-185) headset. There are two available. 

These are a high quality dedicated softphone headset (USB connection only to the computer) designed for use with Skype for Business, 3CX, 2Talk, etc Voice over IP VoIP telephony.  I bought these to try out a softphone solution for work, but ended up sticking with desk phones. This was used for about a week and then put back in the box, so it is in as-new condition. Buy with confidence. 

Note I paid around US$160 each for these from Amazon just over a year ago. The power adaptor is a USA model that supports 110-250v, and I've 'tweaked' the prongs to fit in a NZ power socket for one of them, and the other one has a travel adapter with it.

 

I would ideally like $100 each.