: This is the Release Group tag. While "FLT" historically stands for Fairlight (a legendary game cracking group), in modern file-sharing, it can occasionally be used as a shorthand or unrelated identifier for specific video encoders.
: This indicates that the total release was split into multiple parts to make downloading easier. You need all parts (part01, part02, etc.) to successfully extract the final video file. Technical Summary Primary Content Video (Likely .mp4 or .mkv once extracted) Studio Girlfriends Films Series Ultimate Lesbians On The Cam Release Date October 22, 2019 File Type RAR Archive (Segment 3) Usage Instructions GF191022-ULOTC-FLT.part03.rar
Based on the standard naming conventions used in these communities, : This is the Release Group tag