The national flag of Bahrain is a red flag with a white stripe at host limited by a serration (i.e. a zigzag) made of five white triangles. It is very similar to the flag of Qatar, except Qatar uses a dark brown colour instead.
There are now only 5 serrations compared to earlier versions of the flag with more than 5 serrations. The five triangles representing the five pillars of Islam.
Fondest memory: Source: Flag Of The World