Master Magnetics Ceramic Round Base Magnet with Knob Pack - Heavy-Duty Strong Magnets with Knobs for Home and Work - 16 lb Pull Each - Nickel-Plated - 1.43" D - 0.98" H - Chrome - 4-Pack

Product overview

Master Magnetics Round Base Magnets with Knob (4 Pack): What to Know

Hold a magnet to the physics and it is the most honest product here. These are ceramic, which is to say ferrite, magnets seated in a nickel-plated steel cup, with an easy-grip knob on top so you can place and pull them without fingernails. Master Magnetics rates each at 16 lb pull on clean, flat metal, specifies 1.43 inches diameter by 0.98 inches tall, and includes non-scratch liners so the cup does not mark a painted or finished surface. No tools, no hardware, no residue, and they come off and move whenever you want.

The manufacturing detail is unusually specific for a consumer magnet and it is the reason to prefer a named brand here: strontium carbonate and iron oxide, molded, sintered at 2,000 degrees F, precision-ground with a diamond wheel, then magnetized. That matters because cheap ferrite magnets vary enormously in actual field strength for the same stated size, and process control is the difference. Master Magnetics is a US company and has been in this business since 1976, which is a longer track record than most of this page combined.

The caveat is in how pull strength works, and it applies to every magnet, not just this one. The 16 lb figure is measured pulling straight away from a clean, flat, thick steel plate. Hang something off the knob and you are loading it in shear, which a magnet resists far less. Paint, dust, a thin panel, a curved surface or a powder-coated finish all cut it further. Read 16 lb as a way to compare magnets, not as a load rating for your filing cabinet, and test with something you do not mind dropping.

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