Magnetic Permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. In other words, it is the ability of a product to be magnetic. It is measured in a unit called â€œÎ¼â€ (Greek letter lower case Mu). It is found in more conductive materials. The more conductive the material is, the higher its permeability. We use a tool called a Lo MU Permeability Indicator made by Severn Engineering. This test is considered non-destructive testing of materials stainless steel. Results are also used on material and product certificates when the customer requests them, or they can be part of our own internal inspection process. A typical application for this test is shackles and fittings used in a mine sweeping application.