Umbul-umbul, also known as rérontek or archaically as tunggul, are traditional flags or pennants found in Indonesia. These decorations consist of a strip of cloth with its longer side attached to a pole.
The items are integral to the traditional cultures of Java and Bali, where they are used for decorative purposes and carried during various festivals. In August, red and white umbul-umbuls are commonly displayed along streets throughout Indonesia to commemorate Independence Day.