The ESI SR1Series Standard Resistors are laboratory standards of high accuracy and stability. Their resistance values are initially adjusted to an accuracy of 20 ppm of nominal, with long term accuracy guaranteed to better than 50 ppm. The SR1Sereis has been constructed to meet today's high standards of performance. The resistance wire used is a modern alloy having excellent stability, extremely low temperature coefficient over a wide range of temperatures, and very low thermal emf to copper. A unifilar winding on a flat mica card is used to minimize both series inductance and shunt capacitance. The durable aluminum case provides electrostatic shielding. Gold plated terminals reduce connection errors.