Right-click the file and select "7-Zip" > "Extract Here" or "Extract to tt555/" to place the contents in a folder.
It is a free, open-source tool that handles .7z and many other formats. tt555.7z
Select your files, right-click, choose "7-Zip" > "Add to archive..." , and set the Archive name to tt555.7z . Right-click the file and select "7-Zip" > "Extract