In a metal ring for a metal belt of a belt type continuously variable transmission, a relationship is established between a compressive residual stress of a metal ring of an innermost layer imparted by a nitriding treatment and a free state radius of the metal ring nondimensionalized by a minimum winding radius. A video call application associated with a phone server receives video call information and provides the information to a video launch application that controls video devices accordingly. The characteristic curve of the measuring element can be changed disadvantageously by solid-matter particles. A first and second impedance matching circuit portions capacitively balance the first and second output terminals such that efficient common-mode rejection is enabled by setting the RC time constants formed by each impedance matching circuit and external resistances to be substantially equivalent.