NILS EXTREME MATT BLACK PU wheels are made of polyurethane. The most important parameters of wheels are hardness and diameter. The hardness of the wheels determines both driving comfort and adhesion to the ground. PU-82A wheels provide good shock absorption and excellent adaptation to any surface. The diameter of the wheels has a direct impact on the driving speed. Larger diameter wheels enable higher speeds, but do not guarantee as much maneuverability as smaller diameter wheels. ABEC 9 bearing, made of high-quality carbon steel, which provides excellent hardness and durability. It is characterized by the lowest rolling resistance, which translates into the highest speed in the American Annular Bearing Engineering Committee standard, ABEC. An important parameter of this bearing is eccentricity, i.e. roundness on the track in the inner ring, and is only 0.0012 mm.