Excellent condition Aero seatpost cap.  I believe it to be for a Trek Madone, but please ask questions and verify your fitment before buying!  Sticker inside indicates it is 160mm in length with a 20mm offset.  No packaging, but I am sure it is new as I see no witness marks of it ever being installed.  Please see pictures for exact condition.  I took a few with the flash and without to try and show the color of the carbon.
Thank you for looking!