This small item is one of the most important tools an electrical diagnostician can own. A power resistor such as this is indispensible in troubleshooting alternator stators. Stators usually fail when stressed, and consequently show good readings when unplugged from the system. This tool, a 2-Ohm, 100-watt resistor, stresses the stator roughly equal to its normal operating load, thereby providing a real-world test of stator output. Simply clip the resistor in parallel with your test meter's leads and check stator output. The resistor costs about $10.