This adapter sleeve provides a mechanical mounting interface for fitting a bearing with a tapered bore onto a cylindrical shaft. The bore diameter is 55.0 mm, net mass is 0.41 kg, and the design is Standard. The sleeve is a complete, mechanical component (FP) intended as an accessory to a rolling bearing rather than a bearing itself. Using the sleeve allows the bearing to be positioned freely along the shaft length rather than at a fixed shoulder, and mounting is achieved by driving the sleeve axially to generate the correct internal clearance reduction. This design suits applications where a shaft has no stepped seat for direct tapered-bore bearing fitting and where the mounting position needs adjustment during assembly. Correct fitting requires measuring the clearance reduction to reach the specified residual internal clearance for the bearing being mounted.