The O rings supplied by us to the defence battery manufacturer have the following application.The O rings manufactured and supplied by us are assembled with a stainless steel screw. This assembly known as vent plug assembly is used to plug [by tightly screwing in] the cell containing potassium hydroxide solution as electrolyte. During charging the cell a slight amount of gas develops inside the cell. During discharging gas condenses to liquid. O ring prevents electrolyte leakage. (enhances the plugging effectiveness). The subject cells made with nickel & cadmium ingredients are assembled as b and are being used in air crafts by Indian Air Force.