Suresh Scientific Works

In physics, a post office box (PO Box) is a laboratory instrument used to measure the resistance of a material. It's similar to a Wheatstone bridge and is used to examine the characteristics of an electric path. A PO Box is a rectangular box made of an insulating material, such as wood or plastic, with two metal terminals on opposite sides. The terminals are connected to a battery and a galvanometer, which measures the flow of electrical current through the material. The box also contains coils of wire that are wound non-inductively and mounted in the body of the box. The resistance arms have a number of coils from 1 to 5000 ohms, plus a plug for infinite resistance. The ratio arms are each 5, 10, or 20 ohms. 

A resistance decade box or resistor substitution box is a unit containing resistors of many values, with one or more mechanical switches which allow any one of various discrete resistances offered by the box to be dialed in.

Prices Will Vary According to the product , Please Connect for More Details for Purchasing, We Have Good Quality of product.