This unit guides and tensions roller chain by combining a sprocket with an integrated bearing support, allowing free rotation on a fixed shaft or axle. The sprocket is made from steel or sintered iron, with a bore diameter of 16.2 mm and an outside diameter of 40.0 mm. Net mass is 0.2 kg. The integrated bearing support lets the sprocket rotate freely under chain load without a separate housing, simplifying mounting on a shaft of matching diameter. Its compact outside diameter and low mass make it suitable for use as an idler or tensioner within a chain drive layout where space and weight at the mounting point are limited.