Wash's green flightsuit from Firefly has long sleeves, and it is normally worn with one of his Tropical Shirts.
More pictures after the break:
One more promo picture:
Screencap from Jaynestown:
Screencap from War Stories:
Screencap from Trash:
Screencaps from The Message:
From Heart of Gold:
Again, almost always worn with his Tropical Shirts.
Thanks to Moara for pointing out this Behind the Scenes pic from Trash:
Edited to add: I was watching some old Youtube vids of the NerdHQ conversations at the San Diego Comic-Con, and Alan mentioned at the Firefly Conversation that he got to keep this flightsuit and it was his favorite. Just thought that was fun. :)
My Photobucket Album for Wash.
Serenifly Costumes site for Wash.