It has an elastic thread, so it can also easily be worn as a bracelet.
The string of beads is mainly used to count repeated mantras. So it actually serves the same purpose as a rosary. Beads made of semi-precious stones, pearls, bodhi seeds or wood may serve all kinds of goals, like counting any mantra, or other forms of prayer, bows, walk-rounds and such. The cord is the same for every mala, and should be made of nine threads, symbolising Buddha Vajradhara and the eight Bodhisattvas. The larger bead at the end stands for wisdom, realising emptiness, and the cylindrical bead on top of the large bead symbolises the void itself. Together, they symbolise the triumph over all adversities.