Inductive proximity sensors are non-contact devices designed to detect the presence or absence of a ferrous material, with the ideal target being mild steel at least 1 mm thick and the same diameter as the sensing face. Due to the limitations of magnetic fields, inductive proximity sensors have a comparatively short sensing range, from fractions of millimeters to 60 millimeters on average, although longer-range specialty products are available. Inductive proximity sensors are available for either shielded or unshielded mounting (flush or non-flush). With special designs and IP ratings as high as 67 and higher, they are capable of withstanding the buildup of contaminants such as cutting fluids grease and non-metallic dust, both in the air and on the inductive proximity sensor itself.