From Fender:
The sound of Fender’s flagship instruments. Fender Ultra Noiseless pickups are the pinnacle in stacked single-coil design, crafted with new winding techniques for livelier and more expansive tone. Alnico 5 magnets with polysol wire deliver a vintage voice with classic bell-like chime without the 60-cycle hum.
Ultra Noiseless Vintage Strat SSS pickups feature lower output for classic Stratocaster tone with no hum.