If there are two things guitarists who swap pickups, with any regularity, should have on hand, it's an LCR meter for measuring inductance, and a magnetometer for measuring Gauss strength. Unfortunately, the cheapest of either costs about $100, either the DE-5000 for the LCR meter, or this magnetometer, the "WT10A". I bought one, and it works pretty well. A benefit to having a magnetometer is that you can check your AlNiCo pole pieces to ensure they're fully charged, and that none of the pole pieces are substantially weaker than they should be. You can also deliberately degauss your AlNiCo magnets in order "age" them, and a magnetometer allows you to gauge the degree to which you've degaussed them. It's also just fun to have an electronic instrument that lets you see things things that are otherwise invisible; you can see how magnetic strength decreases with distance, or compare the strength of various magnets, or pickups, to one another. It's the sort of thing you start to find uses for once you have one on hand. Another particularly useful thing a magnetometer can do is help determine if an AlNiCo bar is AlNiCo 5, or AlNiCo 2, 3 or 4. AlNiCo 5 will show nearly twice the strength of the lower grade AlNiCos. Strat / Tele pole pieces usually read about 1000 gauss at the tops of the pole pieces, while lower AlNiCos read closer to 650 to 750. And yet another great benefit is that it simply tells you the polarity of the magnet, very helpful if you're trying to determine which pickups within a set a set are RW/RP, or if two pickups from two manufactures are magnetically in or out of phase. It's a lot more classy than using a compass. The WT10A technically outputs milliteslas instead of gauss, but the difference between the two is just one decimal place. 1 millitesla = 10 gauss. It features a "zero out" dial, a 2000mT / 200mT precision button, and mysterious "check" button. The plastic enclosure definitely has the Chinese thrift look and texture, but it seems to be sturdy and reliable none the less. Considering other hand held magnetometers on the market cost upwards of $500, there's very little to complain about. Here are some pics of the WT10A: Comes with a decent case, and a power supply, which is a very nice touch, considering the price point. An AlNiCo 5 pole piece measuring 116mT, or 1160 gauss. A small stack of neodymiums measuring 426mT / 4260 gauss, much stronger than the AlNiCo 5 pole piece. An SSL-1 with pole pieces that I had degaussed: Another magnetometer agreeing with the measurement of the WT10A: Note that when measuring magnetic strength, particularly when the faces of the magnet are small or narrow, the value tends to bounce around a lot as you try to find "on center" for the face of a magnet, or any other orientation relative to the faces. There is also a time lag factor as the circuitry calculates the flux density based on the Hall effect sensor. Due to that uncertainty, it's hard to say that a magnet has a particular guass strength, and instead you end up having to round of, with a margin for error of +/- 5mT. In summary, very good deal.