Off Topic Productions

I found a mod on Mod DB allowing you to spawn a partner who could assist you in fighting and stuff, who also follows you, but it was in a .rar file which I can't open... Can someone send me a link to download a file opener that opens .rar files, please. It would be quite useful.

P.S. Something that I don't have to pay for, please...

Thank you...
Very Helpful!