The depth of the bonded seal can be less and the space between the bore and the outside diameter can be changed for ease of fitting. The bonding of rubber to metal is an important factor to be considered in the manufacture of such seals and should be considered carefully, since failure of the bond will cause the seal to fail. The metal case of the oil seal is usually made from mild steel of deep drawing quality which enables blanking, punching, stamping of the steel to the required dimensions.