the flow of liquids in pipelines plays an important role in industry and commerce. Under most circumstances it is essential to know whether or not there is a flow in a pipeline, and to act upon that knowledge. That is the reason for, and the function of, mcdonnell & miller flow switches. Includes 4 stainless steel paddles: 1″, 2″, 3″, 6″. Nema enclosure type 4x. Watertight, dust tight and corrosion resistant.