Step into Hollywood's famous Museum of Illusions and Upside Down House and you'll be sure to baffle your friends with our optical illusions! When you move your head closer to or farther. When was the last time you read a story where the villain was celery? Probably the best optical illusions and fascinating visual phenomena emphasizes interactive exploration, beauty, and scientific explanation. Extra large orifice/Special hazard; Coverage per NFPA 13; Available with optional dust and air seal; The ILLUSION is concealed in an enclosed escutcheon.