A Bajoran betrothal bracelet, also called a pledge bracelet is a bracelet given by a Bajoran male to a female to whom they are engaged to be married. It is someone similar to the human practice of a male giving an engagement ring to a female that he intends to marry.
The bracelet is often passed down through families. When Lwaxana Troi fell ill and began projecting telepathically throughout the station, Vedek Bareil Antos was one person affected, and became attracted to Jadzia Dax. He tried to offer Dax a pledge bracelet that had been in his family for quite some time. (DS9 episode: "Fascination")