This is a large 1 3/8" diameter 35mm fancy metal ring , (about a size 26) with the wording "Jack Earle Giant 8ft. 6." on the face.
Jacob Ehrlich was born in 1906 in Denver, Colorado and became known as Jack the Giant. Jack Earle was one of the world's tallest humans and for 14 years, he traveled with Ringling Bros. and Barnum & Bailey Circus. At the circus, Jack would stand at a side show wearing a ring like this. For a fee, a patron could purchase the ring and Jack would let them remove it from his finger.