The N rating is what the magnet industry uses to differentiate between magnets of different strengths. The number (measured in megagausse Oersted) represents the maximum energy product of a magnet, which is a way of measuring the strength that magnets of a specific composition can be magnetized to when manufactured. Orders of Magnetude sells N35 neodymium magnets. Other compaines sell a selection of different magnets. At least one company in particular (we won’t mention names) sells N42 magnets, arguing that anything less is inferior. This argument is foolish, whether intentional or not, as neodymium magnets come in a range of n values ranging from the thirties to the fifties. The problem with simply acquiring as high an n value as possible, is that the graph of n-values to dollars is not linear. That is to say that if a person wants a magnet with a pull force that is twice as large as a comparable magnet of a specific n-value, they will pay more than twice as much for that magnet, as manufacturing exceptionally strong magnets is much more difficult. This does not mean, however, that N35 magnets are weak (the 1″*1/8″ disc magnets have a pull force of ~45lbs between steel plates). It does mean that if you need a magnet of a specific strength and space is much more of a luxury than money, you are better off buying a magnet with a higher n-value. For most uses however, if you require more strength, purchasing two magnets will save money and allow for a more evenly distributed magnetic force (you wouldn’t secure a board on a deck with a single, very secure, screw).