The IEC Resistance Coil is a classic item in teaching electrics. It consists of a coil of temperature stable wire cut and wound to accurate resistance value and connected to terminals on a small transparent housing. They are designed for use in resistance measuring bridges and similar and are not meant for large currents. Each can dissipate about 4 watts for long periods or about 10 watts for a few seconds only. Avoid running them hot. Standard values are: 0.5, 1.0, 2.0, 5.0. 10.0, 20.0, 50.0 and 100.0 ohms. They are calibrated to an accuracy within 1%.