Guy's Magnets 20 mm x 8 mm x 5 mm PNI8 grade bonded neodymium block

+/- 0.1mm manufacturers tolerance on any dimension Magnetised through the 5mm thickness so that one 20x8mm face is north, the other is south

Guy's Magnets 20 mm x 20 mm x 5 mm N42 neodymium block

+/-0.1mm manufacturers tolerance on any dimension Magnetised through the thickness so that one 20x20mm face is north and the other is south

Guy's Magnets 20 mm x 4 mm x 2 mm N52, high grade, neodymium block

+/-0.1mm manufacturers tolerance on any dimension Magnetised through the thickness so that one 20x4mm face is north and the other is south

Guy's Magnets 3 mm x 3 mm x 20 mm neodymium block

+/-0.1mm manufacturers tolerance on any dimension Magnetised through the length so that one 3x3mm face is north and the other is south Note the pull and hold calculations are from the mathematical formula for this grade.  This does not take account of the fact that they can be more easily removed than expected as the length acts as a lever.