N42 Neodymium Magnet for Arts, Crafts, Model Making, DIY, Hobbies, Office and Home - 30mm x 10mm x 5mm thick - 8.1kg Pull - Pack of 4

I have been working on a sensor for monitoring 3d printer filament dry boxes and have tried a number of methods of attaching the sensor inside the box. This attempt I used magnets, one magnet on the outside (which I would stick) and then a magnet attached to the sensor. The picture here was a simple test, where no glue was used, simply one magnet on the outside and one on the inside, behind the plastic on the lower box. There's approximately 4-5mm of plastic in-between the two magnets and the force that the box is being held with is incredible, I have added considerably more weight (than this) and the thing still does not budge, which is remarkable given the gap and the "slipperiness" of the box itself. The only negative is the price of these magnets, they're really expensive, but I guess you don't get high quality magnets like this cheap. I ended up buying more of these because of how impressing they actually are.

Very small and light but very strong. I originally bought it as an experiment to manage wires behind plasterboard but unfortunately not strong enough for that however.. - Because I have steel joists this is an excellent tool to find out where they are behind the plaster board as it sticks to the wall where they lie - I had an Ikea cutlery rack which I installed years ago and placed one of these on the back of the steel channel and now it acts as a magnetic catch for my big knife.

These are Ok. Quite strong wee magnets that'll snap together with some of your skin inbetween if you're not careful. Managed to retrieve a lost retaining nut that was rattling around in my vac's aluminium handle. ..edit. using all 4 of these I managed to remove a House of Fraser security tag which they left on a mail order jacket.

Perfectly good, strong, product as expected & prime next day delivery worked. Need them for pinpointing locations either side of mounted plasterboard... i can put two either side of 18mm timber and drag the one along by the force of the other. PS: I have read about magnets being brittle and chipping - I cannot see this happening with these unless handled really without due care.

Absolutely no doubt that these are very, very powerful magnets. So powerful that it can nearly be impossible to remove them from a very flat metal surface. But one has broken already by just falling on the ground. From examining the 2 halves it seems the metal is a cast type metal, which can be brittle.

Proper sticky... didn’t listen to the warnings on the packet and gave myself a blood blister within 5 minutes of opening. Honestly, the snap on them is a rival for a saltwater crocodiles bite. Also works for holding letters to ignore on a noticeboard in the kitchen.

Very good quality product, strong and exactly as advertised. Fast delivery is always a bonus. I used this magnets to make nets for my car windows and the work a bit better than perfect.

I have to say these magnetes are very strong. However very brittle too. They broke in half immediately i tried to seperate them. I recommend you dont buy them. I would like my money back as they are usless to me now.