GoldenHorse Multicolor Light Up Quad Roller Skate Wheels - Yellow Urethane Quantity: These can be purchased in sets of four or 8 wheels. Size: 58mm in Height These wheels Light Up in 4 Colors - Red, Blue, Green, & Orange Not recommended for use on very small childrens skates. They require contact with a smooth surface to light up. (In other words you can't hold one and just spin it; you need to skate on them.)