These are wheels that light up when you run. I received them as a prize and have been storing them for several years. The wheels may not light up due to the passage of time. The bearings in the center may also be deteriorated. Diameter: Approximately 5.5 cm Width: Approximately 3.5 cm Diameter of the center hole: Approximately 7 mm *Measurements are approximate. Set of 8 clear and yellow dome-shaped roller skate wheels. - Quantity: 8 - Color: Clear/Yellow - Type: Roller skate wheels - Material: Plastic - Shape: Dome-shaped Thank you for viewing. #RollerSkates #Wheels #RollerSkateWheels