200 Denier Nylon: This is the standard flag material in the United States. Most US and state flags you see are made of nylon
All promotional event flags have a "bleed through" where image is seen, in reverse, on the back side of the flag. We call this "Single Face Reverse" or "SFR". About 90% of the flags we make are single face reverse. Almost all state and country flags are made this way, even the ones with writing.