This listing is for a Traditional Tibetan embedded yak bone mala. There are 108 embedded yak bone beads on the string. Each bead measures 5mm thick and 10mm diameter and has two brass counters which has bell shaped bead and dorje shaped bead as pictured.
Prayer beads usually used for meditation, counting mantras, prostration and so on. Wrist malas are used for prostration especially. Malas are worn on the left wrist while not in use. You can usually see monks using malas in those Tibetan monasteries around the world. In those Tibetan Buddhist philosophy university, monks use the regular mala for debating. Just let me know if you have any other questions.