Summary: The 2.5mm-USB adapter is the silver lining. I had an old 2.5mm Jabra hook collecting dust and somehow remembered it when the new headset's mic died. While the adapter might not have been the intent of the purchase, what I ended up with works great.
Pros: My trusty Creative Fatal1ty's mic gave out after two years of abuse. Since its speakers still work for media, I figured I'd go for a lighter single-ear headset. I've got a deep respect for Plantronics after my call center years, so a little hunting brought me to this little gem. Decent audio qual...
Cons: Note the past tense in that last line. Mic suddenly dropped to near inaudible levels within four hours of unpacking. Checked on two other computers and fiddled with the output switches to be sure, it's pretty much dead.
Excerpt: This is a very comfortable item. Flexible, behind the ear suport, adapts to the ear for easy ware. Both earpeice and microphone sound are good. The length of the cord is too short for use with a desk mounted phone.
Pros: good sound quality, Comfortable, easily adjustable to either ear