Guides and tensions roller chain through a fixed idler position, running on a sintered iron or steel sprocket mounted on an integrated bearing unit. Bore diameter is 16.2 mm, outside diameter 40.0 mm, net mass 0.21 kg. The compact housing-free design keeps the sprocket and bearing as a single unit, simplifying installation directly onto a shaft or pin without additional mounting hardware. The integrated bearing supports the sprocket under the radial load generated by chain tension, allowing smooth rotation at the idler point of a chain run. Its small outside diameter and light mass suit installations where space along the chain path is limited. As a unit combining sprocket and rolling bearing, it requires no separate lubrication of a mating bearing seat, reducing maintenance points along the chain drive.