The IEC Decade Resistance Box is a classic instrument in the electrical lab. Resistance is dialled up in decades and a pair of 4mm spin free IEC terminals allows a low resistance connection. An earth terminal is fitted also to the housing. There is a large range of 3 dial, 4dial, 5dial and 6 dial boxes covering many ranges. The value of each resistor is calibrated to better than 1% accuracy, with the exception of the 0.1 steps which are within 5%. Each step can dissipate 1 watt of heat.