Payments in cash are submitted to a merchant at a point of sale. Nuts are seated on the at least one threaded spindle and engage the spindle sections, respectively. An inflation lumen is coupled to the support structure to inject an inert, insulating fluid in the support structure, thereby expanding the support structure and the expandable membrane, wherein the resultant expansion chamber formed therebetween is substantially conical in shape. The selector switch also has an RF channel connector for making a connection with a radio frequency unit of the magnetic resonance apparatus; and a switching unit to make a radio frequency connection between one of the antenna connectors and the RF channel connector.