To activate the LEDs in your Flashing Bounce Rainbow Crazy Cube, just throw it down on a hard surface. Bright lights will flash on & off, then shut off automatically. Dimensions: Height: 1.75 in. 4.44 cm. Width: 1.75 in. 4.44 cm. LED Colors: 1 Blue, 1 Red Comes ready to use with non-replaceable batteries; sealed inside for child safety.