An Ateco round cake mold (48710). Official catalog: 9.5" diameter, 3" high, stainless steel, no joint or seam, made in Taiwan. Listed under Round Cake Molds; catalog also lists layered desserts or foods. Specs from Ateco's catalog PDF, Round Cake Molds table.
A 9.5-inch seamless ring, 3 inches tall. Stack a layered cake or a savory ring.