The Genrad 1407D is a standard capacitor that consists of a silvered-mica and foil stack which is clamped under heavy spring pressure for mechanical stability. Sealing the mica capacitor in the case with a desiccant makes it possible to reduce the insulating material, other than mica, to a minimum. The only insulation except mica and dry air is a Teflon bead in the connector and a small amount of low-loss rubber in the gasket sealing the connector.