From the Seymour Duncan website...
"We build this pickup exactly as they did in the old days for all the chime and bell tone enjoyed by Stratocaster players in the 50s...Our Vintage Staggered for Stratocaster uses hand ground alnico 5 rod magnets and heavy Formvar magnet wire with a special wind pattern to produce that bright, glassy, bell tone with all of the bounce and sparkle youd expect from the best 50s Strat pickups. The treble attack is crisp and immediate, while the low end remains articulate and focused. Chords ring out with clear note to note separation. Use a full set for a truly vintage vibe, or use in the neck & middle with a Custom Staggered in the bridge for a more rocking setup.Since 1978, we've been building all of our vintage Fender style single coil pickups just as it was done in Fenders Golden age. We start with the right color and thickness of Forbon flatwork, with the traditional keyed bottom plate. Then we hand file the flatwork, assemble with hand ground magnets, and lacquer the bobbin. After winding, each pickup is wax potted to reduce unwanted squeal, and comes with waxed and tinned cloth pushback hook-up wires and traditional keyed bottom plate".
Full details and sound samples.