Here's what Seymour Duncan say about the STK-S4m:
The Classic Stack Plus middle pickup looks and sounds like a true Stratocaster single coil but none of the traditional Strat hum. It has all of the sparkle and chime that you would expect from a vintage Strat pickup.
We build it RWRP to give you that perfect in-between sound of positions 2 & 4 when split. It has a special bottom coil that actually injects negative hum into the pickup circuit, and, at the end of the production process, we fine tune each pickup for maximum noise cancellation.
You get all the great qualities of a classic Strat pickup, and none of the hum. Pair with our Stack Plus bridge and neck for a complete set.Hand built in Santa Barbara, CA, it uses hand ground alnico 5 rod magnets, and comes with a splittable 3-conductor lead wire to give you access to true single coil operation. Each is wax potted for squeal free performance.