CMS MAGNETICSMagnetic Pole Detector, a Handy Polarity Identifier to Determine Magnet's North or South Poles, Great for School Teachers, Science Projects, and Metal Detector

This product perfectly tracks the pathway of a magnetic field from one pole of a magnet to another. It also works great for locating the poles on a piece of magnetite. I have a chunk of magnetite that has four poles, and it quickly finds and identifies them. It would have to be a very powerful magnet to identify the pole from a couple feet away. I have a 6" x 1" bar magnet, and it picks that up a foot away. But to show the magnetic field is parallel to the body of the bar magnet it needs to be about an inch away on the sides. I go past the end of the magnet a couple of inches and it definitely shows the field orientation. If the magnet in this sensor gets stuck to a bigger magnet, use care separating the two. Slide the sensors magnet to the edge - don't just yank it off! The product advertising does state that this device is 4.75" long, but I missed that. When I opened the package, I was expecting something a bit longer, but that's on me. The compact size does not detract from the operation at all, and it does make it easier to slip into a shirt pocket. This product is a delicate instrument and should be treated carefully. This is not a defect, pivoting a magnet in two axises requires some small parts. Treat it carefully and will reward you with years of service. Give it to careless kids and it won't last. I like it and will order a couple more. I think you will like it too.h

simple and works

Inexpensive, but I will need to find a box to put it in.In an interesting way it also identifies to a certain degree just how strong the magnet it.It snaps for strong batteries and you can also read its magnetic field as you move it away from the magnet. It was very interesting. Glad I bought, but I do need to find a better safe keeping spot for it...

Moves when close to magnets. Doesn't work as compass.

The polarity/field direction sensor was just about exactly what I expected. It is intended to map out the fields of actual magnets and is barely able to sense Earth's 0.5 Gauss magnetic field. However, it was good enough to give a positive indication that the red end is actually itself a south pole and it points toward north. The polarity diagram shown is backwards. I had already marked a magnet based on a compass and that agreed with this polarity. As noted, the bearings are both a little delicate and have some friction. I put a very tiny drop of ultra-fine clock oil on the two brass pivots and it helped a little. Don't put oil on the plastic bearings, as it might degrade the plastic. The plastic outer bearings are a little crude, but seem to work OK with real magnets. Be very careful not to touch the rotor to any strong magnets. It won't hurt the magnet but could easily damage both sets of bearings. Very useful product.

we have purchased dozens of these n - s pole checkers over the years. we never had any quality issues until the past 2 orders... on the first problematic order, the magnets were damaged, and had had magnet dust and grime on the magnets. on the 2nd problematic rotor, the magnets did not easily rotate in the middle point supports, which is key to the function of the pole checker. I kept the parts from the first problem shipment, because I was able to use masking tape to clean off the powder grime. The 2nd order had to be returned. I would be willing to purchase again from this supplier, but not without reassurance that the quality problems are fixed.

Handy magnetic tool

Every 3d printer enthusiast who uses magnets in their prints needs to know these exist. I've wasted so much time trying to figure out which side is which on my magnets and this solves it with a single quick glance. It's nice and compact and feels quite sturdy.