The iButton can is made of 305 stainless steel, which is non-magnetic. However, some iButtons have an internal battery that does enable it to be picked up with a magnet. The issue is that the internal construction of the iButton contains a spring attached to the battery of the device. The presence of a strong magnetic field may lead to the dislodgement of the spring. We have not performed any studies on this and so cannot provide any guidance on the size/strength of the magnet which causes the spring to move.