Guides and tensions roller chain runs through an integrated sprocket mounted on a rolling bearing, allowing the sprocket to rotate freely under chain load. The unit is built around a 20.0 mm bore with a 47.0 mm outside diameter, giving a compact radial section for chain guiding applications, and the complete assembly weighs 0.37 kg. The sprocket body is manufactured from steel or sintered iron, depending on the production batch. Being a self-contained idler unit, KSR20-B0-10-10-17-15 simplifies chain drive layout since the bearing and sprocket are supplied as one preassembled component, reducing the need for separate mounting of a bearing and a wheel. This construction suits chain guiding, tensioning, or return points where the sprocket only follows the chain without transmitting drive torque. The fixed bore size and outside diameter make it suitable for direct shaft mounting in installations designed for this dimensional combination.