An opening in a substrate is formed, e. The apparatus comprises at least one elongated flexible member, and a plurality of stones connected to each other by means of the at least one elongated flexible member. The method may also include allocating a graphical element to the first display or the second display based on characteristics of the graphical element. Further, the invention relates to a system for identifying the ions. The feed shaft further includes an opening transverse to the axis. Cancellation of parasitic capacitance is provided for differential mode and common mode split windings where the split windings may be either inductively coupled or not.