Be cautious when opening .7z files from unknown sources. Because they can contain any type of data—including executables or scripts—always scan the extracted contents with updated antivirus software. WinZip Opens & Extracts 7Z Compressed Archive Files
This format supports AES-256 encryption . A key feature of 7z is the ability to "Encrypt file names," which prevents anyone without the password from even seeing what is inside the archive. Arab.7z
Since I cannot browse the specific contents of a private file, here is a general review of the used to create it, highlighting why this specific file type is often chosen: Format Review: 7z Archive Be cautious when opening