Spacers are metal rollers put in wheels between bearings in-line skates, skateboards and scooters. They provides correct spacing of bearings centres in order to avoid their delfection from circuit (this would lead to slowdown of bearings). Wheels without spacers will hardly rotate. Diameter of wheel screw (screw which goes throw the wheel and chassis) need to be known for correct choice of spacer. It is offered with diameter either 8mm or approximately 6mm.