Ron Bauer series The Cursed Ring #8
From the man who has left his ring in more than three-hundred restrooms!
You can't rid yourself of that ring! It vanishes from a volunteer's hand, and invisibly returns to your finger! Or does it? Even under "test conditions" it happens again!
Learn the subtle secret of using one method to throw the audience off the scent of the next.
16-page staplebound booklet."