MARIC FLOW CONTROL AUSTRALIA is an Australian manufacturer established in 1963 by Eric Schroeder, and still in that family. The Maric Flow Control operates to maintain a steady rate of flow over a wide pressure range by the use of rubber orifice, which varies its aperture with pressure change. This is very useful for any equipment requiring a fixed flow rate. Especially useful for submersible bore pumps of limited capacity, which is where we use them most, to prevent the bore being over-pumped. Because they are of a fixed capacity, the flow rate cannot be varied by altering a setting, making them full-proof protecting from ignorance or vandals. Modestly priced, in brass or stainless steel, and threaded or flange installation. A very good addition in the appropriate situation.