Refined by Les Schatten especially for guitar shops, the Schatten Magnet Polarity Tester is useful for troubleshooting and testing pickups and wiring.
Pickup rewinding specialist J.M. Rolph has noted, "How many times have you wired a pickup and found it's magnetically out of phase, with the same thin, low-powered sound as a pickup that's wired out of phase, even though the lead wires looked right?" By indicating the north or south magnetic orientation of a pickup's polepieces, this polarity tester can help you avoid the problem.
With a basic knowledge of vintage pickup magnet polarities (instructions are included), this tool is also a quick way to determine a pickup's authenticity.
If you do a lot of work on guitar pickups and amp electronics, you'll want this simple and effective tool in your toolbox.