The listing, USA #U543 1960 Pony Express postal envelope, mint has ended.
Features the Pony Express design
Catalog # U543
Condition: post office fresh
I have several of these, all identical, the scan is representative of what you will receive.
My general terms for stamp-related Listia lots can be found here (please read, it answers a lot of basic questions):
http://listiarules.webs.com/