[Diameter & Note] - Bearing inner diameter 8 mm, gasket inner diameter 6 mm. Note: The spacer is suitable for 6 mm shafts, but if removed, the wheels can fit 8 mm shafts. Shafts and screws are not included in the package. [Wheels] - These wheels are designed for luggage, training wheels, or children's indoor roller skating. Not recommended for use on uneven surfaces. [Sturdy Material] - Made from high-quality PU material, these rollers are wear-resistant and durable. Designed with a hardness of 82A for long-lasting performance. High-performance bearings ensure stability and comfort. If the inner buckle of the wheel core is loose, it is recommended to insert a small piece of paper between the white plastic lip and the bearing to secure the wheel more firmly. [Ultra-Quiet Design] - High-elastic material allows smooth and quiet movement, enhancing the skating experience. Color: Black Material: PU Size: 64 x 24 mm Package Contents: 8 x Inline Skates Wheels Note: The package includes only the items listed above. Other products are not included. Light and display differences may cause slight color variations between the image and the actual item. Measurement error is +/- 1-3 cm.