The arch shaped object is incised with floral designs and the eight auspicious Buddhist symbols; a wheel, a conch, an umbrella, a victorious banner, a vase, a lotus and an infinite-knot. The center of the amulet is open which generally can contain a painting or image of a protective deity.
Amulets or Charms are generally worn by nomads. Although it is worn as an ornament, but it is also a protector of life because it holds protective contents, such as images, relics, blessed pills or grains of rice, miniature paintings etc. Though the tradition of amulet wearing was not in practice in early Buddhism, however with the rise of Tantrism it came into practice, particularly by the northern Buddhists.
This description by Dr. Shailendra Kumar Verma, Ph.D. His doctorate thesis being on the "Emergence and Evolution of the Buddha Image (from its inception to 8th century A.D).