Maritime Flag U — Uniform Throw Pillow

This maritime flag represents the letter U (called "Uniform") in ICS (International Code of Signals) and NATO maritime standards. It can be used with other flags to spell a message. In ICS, a single U flag can be used to indicate "You are approaching danger." The U flag can be combined with other flags for specific shorthand messages such as US4, which means "Nothing can be done until the weather improves," or UM, which means "The harbour is closed." "U" is the 13th most commonly-used letter in English. Write your own messages with U and other maritime flags!