Rheostats are mainly used for regulating electric current in industry and laboratory where these are used as adjustable resistors in electrical circuits. With three terminal provisions, these can be used to vary a D C potential smoothly from zero to maximum. Toshniwal Rheostats consist of resistance wire wound on a former which is made from solid drawn hexagonal steel tube vitreous enameled, ensuring good mechanical strength and sturdiness. The tube is fitted in two end castings insulated with micanite cups. The Brush gear slides on a highly polished square slide rod. The brush is of copper graphite with pigtail connections. Two heat resisting compression spring hold brush family in contact with the resistance wires. Copper graphite brush provides necessary lubrication to prevent wear and tear of wire even at elevated temperatures. The brush is housed in a slider knob of moulded bakelite designed for easy handling. Different designs in a single tube and double tube models are available to meet with demands of different applications. In many applications larger values of resistance are required to be accommodated in small space but at the same time the current rating desired varies for lower to the higher values of resistance. For such requirements Rheostats are also available in space saving graded winding designs. For requirement of graded Rheostats desired resistance, voltage, maximum and reduced current rating should be stated. Lead screw type Rheostats are also available for precision and smooth setting of brush position using hand wheel provided axially or at right angles to the lead screw which replaces the slide shaft in this design.