This is the new Paddle Handle to fit the FathomII 15 Level Wind Model but it will also fit most of the Mk1 Fathom Star Drag and Level Wind models up to the 25n. If you are not a fan of the std Handle on the earlier models then this may be the answer for you.
Penn style No 024 FTHII 15LW - Part No 1490338.
Please check your schematic to ensure this is the correct part for your reel.