: You cannot open this file alone. You will need all subsequent parts (part2, part3, etc.) in the same folder to extract the contents.

: Always run the archive through a service like VirusTotal before extracting.

: Limited-time versions of tools or applications meant for marketing purposes.

Depending on where you found the link, "PROMO.part1.rar" generally contains:

In most cases, a file named like this is part of a larger set (accompanied by .part2.rar , etc.) often found on file-sharing sites, Usenet, or private FTPs. What is usually inside?