A method of advertising comprising providing a sheet of advertising material having a front surface, front surface having advertising information thereon. The tunnel spans between a data center and a private enterprise network and connects endpoints, of a service application, that reside in each location. A flat or substantially flat portion is provided around the central hole of the inner case, and a viscoelastic filler is arranged so as to extend from the central hole to the flat or substantially flat portion of the inner case. There’s a time limit to strategically place the secondary pieces inside of the primary pieces and placed on the board. Compared with the conventional technique that diffuses each tone error into the error buffer in response to every occurrence of the tone error, either of these procedures enables collective diffusion of the tone errors with regard to the preset number of pixels, thus ensuring higher-speed diffusion of the tone error.