Right-click the Gridinsoft Anti-Malware 4.2.55.rar file and select "Extract Here" (using 7-Zip or WinRAR). Install: Run the extracted .exe installation file.
If you are looking for specific features or a comparison of this software with other anti-malware programs, please tell me: What are you facing?
While you are asking for version 4.2.55, security software is frequently updated. It is generally better to download the latest version offered by Gridinsoft to ensure you have the newest threat definitions. General Installation and Usage Steps