A resonance frequency adjusting circuit in electronic communication with a power supply and a load connected to the power supply includes a first LC filter, a capacitor, a switch, and a frequency detecting and control module. Receiving surfaces defining a planar end are formed on each of the first and second core halves and extend substantially continuously between opposed ends. The visible data is based at least partially on document data which includes identity data indicative of an identity associated with a region of the interface. The drag reducing additives of the invention are not subject to shear degradation and do not cause undesirable changes in the emulsion or fluid quality of the fluid being treated, or undesirable foaming. Also provided is a method for providing such a plastic composition.