Wheel size and material: 54 mm diameter by 36 mm wide PU skateboard wheels. Bearings: 608RS standard skateboard bearings, the most common standard and compatible with nearly every skate wheel. Bearing performance: bearings can continuously rotate about 30 seconds without load, contributing to a smoother roll. Suitability and ride quality: 54 mm wheels are suitable for beginners when learning on short longboards or cruising; compatible with all ground types including ramps, sidewalks, smooth concrete, and asphalt; deliver a smooth and stable ride. Replacement and versatility: replacement wheels for experienced riders or as wheels for beginner skateboarders. Hardness and durability: 85A hardness PU material for durability, stability, and quiet operation; slides fast and smooth. Material properties: elastic PU that is strong and durable, with elasticity, fast rebound, and higher success rate of action. Use scenarios: Beginners practicing balance and cruising on flat ground. Cruising on city sidewalks, smooth concrete, or asphalt. Light ramp riding and transitions for improved stability.