Spin science into artYou won't believe your eyes or earsDisk will spin faster and louder the longer it goesJust give it a spin and gravity does the restA hypnotic display of light and soundFascinating desktop illusions Spin the holographic diskon the mirror. Does it speed up? Listen to its rhythmic sounds. Why does thehumming get louder as the speed of the disk increases? This patented 3"Diameter chrome-plated steel disk creates a hypnotic display of light andsound as it rotates. Includes Euler's disk, 9" Concave mirror base and ninepieces of magnetized holographic foil. Complete with instructions and thescientific answers From the Manufacturer Give the Euler's Disk This patented3" diameter chrome-plated steel disk creates a hypnotic display of light andsound as it rotates. Includes Euler's Disk, 9" concave mirror base and ninepieces of magnetized holographic foil.