These are resistors with long term stability and close tolerances. These are used in measuring instruments. Wire wound resistors, produced with long term stabilities and with special techniques used to reduce inductive and capacitive effects are precision resistors. The wire used is of Cu-Ni or Ni-Cr alloy, with enamel coating or silk covered with vacuum impregnated varnish. End connecting wires are copper leads, with silver soldered to ends. Small bobbin is used to wind wire. It is covered with ceramic sieving. Due, to winding, these resistors have inductive effect. To reduce it, bifilar winding is used. The wire is bent back on itself at mid point, so that two halves are side by side separated by insulation only. If this loop has multiple layers, then the distributed capacitance is large. It is reduced by winding each bifilar loop on a separate section and connecting such sections in series.