The 25mm neodymium ring magnets in this section may look identical but there is one distinct difference. One is supplied already magnetised and one is supplied unmagnetised. When magnetised, these 25mm diameter N42 neodymium ring magnets produce an impressive maximum magnetic pull of 5.9kg. The reason that we supply unmagnetised ring magnets is because some applications are required to be assembled with unmagnetised magnets which are then magnetised once the application is complete. Identical magnetised and unmagnetised rings can be used to demonstrate how the intriguing 'eddy currents' produced by a magnet and copper pipe create a damping effect. A non-magnetic ring will slide down a length of copper pipe in an instant but the magnetised variation will descend slowly. A great way to bring magnets to life in the classroom.