Methods of forming a graphene material on a surface are presented. The connecting line provides pressure communication between the fuel tanks so that fuel flows from one tank to the other whenever there is an unequal pressure acting on the fuel, which occurs whenever one tank has more fuel in it than the other. The audio output unit includes a magnetic member. The reflection circuit is coupled to the directional coupler to receive the oscillator signal and is adapted to reflect at least a portion of the oscillator signal to the mixer via the directional coupler to counteract a parasitic portion of the oscillator signal received at the mixer. The engaging flange of the envelope is received in the receiving groove. The invention proposes that the damping unit is arranged on the impact mechanism housing along a main extension direction of the impact mechanism unit.