I have a carbon seat post in my collection of left-over bike products that my son bought several years ago which I don't believe he ever used. He can't remember either. He doesn't cycle any more so I'm selling it. I'm not sure of the value, but I set it at $40. Here are the specifications as close as I can determine. Pictures also.

Used Sumo Adjustable Carbon Seat post. This is a used, but is in excellent condition. It shows no wear or marks on the post. It looks visually like it has never been used. (See pictures)
The length: 10.5" (27cm)
Diameter: 1.07" (27.2mm)
Weight: 7 oz.

Please contact me if you have any questions.