What a magnetic spring actually is
Concentric rings of opposing polarity on a magnet face produce a force that changes with the gap rather than a simple pull. Bring the parts together and the force rises steeply; separate them and it collapses. Functionally that is a spring, with the difference that nothing touches, so nothing wears.
Where it genuinely wins
Short travel, high cycle count, and anywhere a steel spring would corrode, collect dirt or need a housing. A magnetic spring has no coil to fatigue, no seat to wear, and it can act across a sealed wall — which a mechanical spring cannot do at all.
Where it loses, plainly
Long travel. The force falls away with distance far faster than a coil spring's does, and by a few millimetres there is very little left. If you need a predictable force across a centimetre, use a spring. Cost is the other one: a coil spring is pennies and a coded magnet pair is not.
Getting the specification right
State the force you need AND the gap you need it at — the two together, not one of them. A part quoted at contact and a part quoted at 2mm can be the same magnet and look like completely different products. Add the temperature and whether it lives outdoors, because those decide the material rather than the pattern.
Off-the-shelf, if that is all you need
Consumer-grade magnets and the tools for checking them are on Amazon, and those links are affiliate links. Engineered Polymagnet parts are not sold there — for those, describe the job and we will quote it.
Neodymium magnet assortmentsMagnetic viewing filmPull-force gaugesNot off the shelf?
Describe what the part has to do — the force, the gap, the material it mates to and where it lives. We will tell you what fits, including when the answer is an ordinary magnet.
Describe the jobMore on the underlying idea: how coded magnets are built pixel by pixel · choosing the material · the catalogue, sorted by behaviour