A dowel for insertion into an opening of a wall, in particular on a vehicle body, has a shank section which extends through the opening in an inserted state and a flange adjoined thereto and made of a first material component, and a sealing section made of a second material component. The present invention is especially effective in a single mode optical fiber which is typical of the step-index optical fiber. An input to the dc bias circuit is coupled to a stage of the power amplifier circuit by a capacitor. In a second phase, the client and server conduct NAT discovery and determine whether the client, server, or both operate behind a NAT. The other of speed or scale to which the output was not mapped is determined according to the relationship that scale multiplied by speed equals a constant value.