CMS Magnetics - Magnetic 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

Works good. Determined magnets polarity for my experiment.

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.

Sweet little magnet. Rather strong for its size, I just stick it to the side of my tool box. The size should not surprise anyone, when you scroll through the pictures you can clearly see that the holder is small. Very nice.

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...

This thing is like 5-6in tall and 3in wide at the top. I thought it would at least be a little bigger than that. So... A little disappointing for that reason, but it works, I think... It's not amazing. It clearly is a $2 item at most if you were to buy it locally, probably a 50cent item to make. Underwhelmed to say the least. Also the magnets aren't labeled with an N or a S, just assumes you know Red = North and Blue = South. Also, for a company that brags about their Environmentally friendly status, this thing came in a large box with a "WARNING MAGNET" label for something that has less gauss than a button cell battery, there's no way this was affecting any sort of avionics or magnet sensitive equipment. Could barely hold a sewing needle.

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.

simple and works

This item works exactly as described. I use it to find the polarity of magnets regulary.