This adapter sleeve provides a mechanical connection between a bearing with a tapered bore and a cylindrical shaft, transmitting the clamping force needed for a secure fit as the locknut is tightened along the sleeve's taper. It has a bore diameter of 25.0 mm and a net mass of 107.3 g, produced in the standard design. The tapered outer surface allows the bearing's inner ring to be drawn up gradually, giving the fitter control over internal radial clearance during mounting and dismounting without requiring a tapered shaft seat. Because the sleeve itself absorbs the fit between bearing and shaft, the shaft can be machined to a simple cylindrical tolerance, simplifying installation on plain shafting while still achieving the required interference fit for the bearing.