When you need to make a load test on your power supply or DC-DC converter or an off-line DC switching regulator these 2 Ohm, 2 Watt resistors are a handy component. You can place these in various series-parallel combinations to get the desired load. For example you want to test a 5V, 1A supply; take 4 of these resistors in parallel to get a 1A load current and test it out. If you need to check the load regulation, you can put 1 resistor followed by 2 resistors in parallel and then 3 resistors and 4 resistors in parallel and know the load regulation.
Similarly, to check a 36V, 300mA DC supply output you can place 6 resistors in series to get a 120 ohm resistor. This resistor would be able to handle a power of 12 watts and so you can easily use it to test the 36V supply.