This is a good quality 6005-2RS bearing that measures 25 mm for the inside diameter (bore). However, if you are trying to replace a 6005 bearing on a 1 inch shaft, such as in certain Warner electric clutches, it will NOT fit. These bearings are made specially with a slightly larger 25.42 mm bore to fit a 1 inch shaft. Since this altered bearing uses the same shields and outer race and cage as the 6005, the shields will show '6005-2RS' (or similar), as found on the original bearing. However, the 1 inch bearing should show a '2X' suffix in the bearing number stamped on the metal ring (e.g., NSK #6005-DUM-2X), which identifies it as this custom and harder-to-find bearing that fits on a 1 inch shaft.