Current Helix, TRS and XCX offerings are all considered Generation 2 cassettes. Gen 2 (sometimes called FW2) cassettes are best differentiated from Gen 1 by the use of a set screw which is found on the largest steel cog and fixes the steel section to the alloy section of the cassette. Gen 1 e*thirteen cassettes did not utilize this set screw.
See below or click here to download the pdf.
Please click below to download/hc/en-us/articles/115003957491-11-Speed-TRS-Plus-and-TRS-Race-Cassette-User-Manual-First-Gen-FW1-Pinch-Clamp-Version
Please click below to download/hc/en-us/articles/210526443-11-Speed-TRS-Plus-and-TRS-Race-Cassette-User-Manual-First-Gen-FW1-Lockring-Version