Reason Studios REX2 Audio File
From Just Solve the File Format Problem
A Reason Studios REX2 Audio File is version 2 of the Propellerhead ReCycle Loop File, used for audio created with Reason Studios software such as ReCycle. The file format contains the audio data as well as any slice and effect alterations created with ReCycle. It is compressed in a non-lossy manner. Unlike earlier versions that had both a native format and an export format, REX2 files are used for both purposes.