The 25mm (0.98") neodymium ring magnets in this section may look identical but there is one distinct difference. One is supplied already magnetized and one is supplied unmagnetized. When magnetized, these 25mm (0.98") diameter N42 neodymium ring magnets produce an impressive maximum magnetic pull of 5.9kg (13lbs). The reason that we supply unmagnetized ring magnets is because some applications are required to be assembled with unmagnetized magnets which are then magnetized once the application is complete. Identical magnetized and unmagnetized 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 magnetized variation will descend slowly. A great way to bring magnets to life in the classroom.