Dirty Dome.
I own a business called www.1570cinemaservices.com that cleans Large Format movie screens and domes. We do all types of screens all over the world. This photo was from a cleaning in late January 2011 of a dome cleaning here in the United States. Your Tree Climbers' Pants are the best built pants we can find for the tough work we do. They take a beating and still look great after washing all the dirt and dust off.
