Below is a guide on where to find these files, what the .rdr format entails, and how to safely install macOS High Sierra. Understanding the .rdr File Extension

Apple generally provides the of High Sierra (10.13.6) through its official support pages.

: If you already have an earlier version of High Sierra, you can download the macOS High Sierra 10.13.5 Update directly from Apple Support to upgrade your system. 2. Community Repositories (.rdr and ISO)

For the highest security, you should prioritize official Apple sources. However, because 10.13.5 is an older version, finding the exact point release can be difficult. 1. Official Apple Channels (Recommended)

: Projects like ihackinOS/MacOS-Collection host various versions, including .rdr files meant for quick restoration.

: You can often find High Sierra through a direct App Store link that may not appear in standard searches.