NEW DESIGN, IMPROVED SPECIFICATIONS
You may also want to consider the SRX Series
The Model SR1 Standard Resistor is a laboratory standard of high accuracy and stability. The resistance of most values is initially adjusted to an accuracy of 20 ppm of nominal, with long-term accuracy guaranteed to better than 50 ppm. Other values have initial accuracy from 50 ppm to 200 ppm.
Model SR1 has been constructed to meet today’s high standards of performance. The resistance wire used is a modern alloy with excellent stability, an 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.
Terminals appear on the top of each unit. They are also brought out the bottom of the case on removable banana plugs. This allows plugging two or more units together in either series or parallel for a wide variety of resistance values. Four-terminal resistance measurements are easily made by using the banana plugs on the bottom of the case as two of the terminals. 0.01 Ω and 0.1 Ω values have four terminals on the top and should only be used in four-wire configurations. For three-terminal or five-terminal guarded measurements, a binding post on top and a banana plug on the bottom provide connections to the case.