Automatic Transmission Oil Pump Seal by National®. OD: 1.565″. Material: Polyacrylate. Width: 0.250″. Housing Bore: 1.561″. Shaft: 1.125″. Redcoat. Don’t just repair a leak, prevent future problems with a National Oil Seal. This part is manufactured using exclusive National Dynamic Edge technology that generates a dynamic pumping action to keep harmful contaminants such as dirt, moisture, etc. out of the seal and other wheel-end components.