This roller chain idler sprocket unit carries a fixed bore of 16.2 mm and an outside diameter of 40.0 mm, with a net mass of 0.55 kg. The sprocket is made from steel or sintered iron, giving the unit a compact, self-contained design for guiding or tensioning roller chain runs. The fixed bore diameter means the unit mounts directly on a shaft of matching size without adjustment, so alignment must be set by the surrounding structure rather than by the bearing itself. The compact outside diameter and low mass keep the unit suitable for space-restricted chain drive layouts where a simple idler or guide element is needed along the chain path.