You are buying tested used OEM Mitsubishi 4 pin relay MR538851 made by Omron in Japan. It fits Mitsubishi Galant, Eclipse, Outlander, Endeavor, Lancer. Applications are listed in the title but the list is not complete. It is a sealed relay.
The relay controls Powertrain ECM in Eclipse, Galant and Montero. This is a multi-purpose relay, can be used for many other applications.