... as F-typeMagnetic inductionMeasure the thickness of Non-magnetic coating layers on magnetic substrate.Such as: (enamel,rubber,paints,plastics ... ,ceramic oxide, Covering layer) on steel,iron,alloy and hard-magnetic steel. Conductive or non-conductive coating layer is unimportant ... oxide layer on copper,aluminum,zinc,tin,non-magnetic stainless steel,gold and silver. Cover layer only can be insulation ...