The helmet appears to be a version of a flight deck crew helmet. I believe the cloth portion of the helmet may have some subtle additional coloration to it to give it the appearance of age. There is also some real dust and dirt on there, presumably from the many weeks of shooting out at Eagle Mountain, where the final battle was filmed.
The style of ear protection varied amongst the costumes, so this small detail may or may not match the "hero" version you see the main stars wearing, but rest assured they are all from the same lot. Be the hit of your next halloween party, comic-con, paintball war or temporal pincer, I haven't seen any other sellers with this item!