Polyurethane (PU) wheels by NILS EXTREME are known for their hardness and diameter, crucial for the ride's comfort and the grip on surfaces. The PU-82A wheels provide good shock absorption and adapt well to various terrains. Larger diameter wheels allow for higher speeds, though they offer less maneuverability compared to smaller wheels. The ABEC 9 bearings, made from high-quality chrome steel, ensure excellent hardness and durability. These bearings feature the lowest rolling resistance, translating to higher speeds according to the American Annular Bearing Engineering Committee (ABEC) standards. A significant characteristic of these bearings is their eccentricity, or roundness on the track in the inner ring, which is only 0.0025mm. Specifications: Wheel hardness: 82A Size: PU 84x24 mm/82A Quantity per package: 4 pcs Bearing class: ABEC 9 Material: chrome steel Number of bearings per package: 8 Number of spacer bushings: 4 Packaging: blister pack Notes: Not intended for commercial use 24-month warranty