From Fender:
The first authentic CuNiFe-magnet-powered Wide Range pickup in more than 40 years delivers rich bell-like humbucking tone with full bass and clear treble. CuNiFe pickups have “hi-fi” clarity yet never lose their attack and definition no matter how hard they are pushed. A chrome cover with a “3+3” exposed pole piece design and Fender logo completes the vintage-’70s vibe.
As popular music roared with the fatter tones of humbuckers at the dawn of the 1970s, Fender hired acclaimed pickup designer Seth Lover to create a distinctly Fender-flavored take on a higher-output dual-coil pickup. The resulting Wide Range pickup used large bobbins and threaded CuNiFe-rod magnets to achieve its distinctively brilliant sound, as heard on that era’s Telecaster® Custom, Thinline and Deluxe guitars. Sought after by musicians of all genres for decades, the original-era real CuNiFe-magnet pickups disappeared when the Telecaster Custom was discontinued in 1979.