An apparatus and method to individually weigh continuously fed mail pieces wherein each mail piece is configured in a vertical orientation and fed through the weighing system in seriatim. The surface acoustic wave device is manufactured by dicing a piezoelectric wafer. The interface includes a method that accepts a first input representative of a selection of a first interface item, the first interface item associated with an entity of the knowledge model. Once the procedure is finished, the deformable member can be drawn back into the tube.