As an example, this oil seal has a part number that corresponds to a Shaft Size of 3”, a Bore Size of 4”, a Width Size of 0.625”, a Style of TB2, and is made of Viton material. Conversely, the same size oil seal in Metric has a Shaft Size of 76.20 mm, a Bore Size of 101.60 mm, and a Width Size of 15.88 mm.