Shields represent protection. The images bring in other energies — the Raven is the messenger between the worlds and the bringer of enlightenment (for example, see the Raven Stealing Sun story). He is the trickster of the Pacific Northwest, somewhat equivalent to Coyote.
While the photo is representative, each shield is handmade, hand painted, and different. The metal hoop is 6" in diameter and covered with deer leather lacing. The shield itself is rawhide, generally deer or horse, and is decorated with assorted beads and feathers.
A kit for making your own shield is available here.