There's a warning here:
http://www.cowmagnetscam.org/#Fraud-Switch-Strong
"Sellers of cow magnets are attempting to pass off a new type of Stainless Steel cow magnet as industry standard ALNICO magnets.
IMPORTANT: this is not an indication of how much a magnet is attracted to regular metal objects (like the metal hardware ingested by cows). Properly designed stainless steel cow magnets may be the strongest available even though they do not appear to stick to themselves with great strength. The real test is to use a GAUSS meter."
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There's a warning here: http://www.cowmagnetscam.org/#Fraud-Switch-Strong "Sellers of cow magnets are attempting to pass off a new type of Stainless Steel cow magnet as industry standard ALNICO magnets. IMPORTANT: this is not an indication of how much a magnet is attracted to regular metal objects (like the metal hardware ingested by cows). Properly designed stainless steel cow magnets may be the strongest available even though they do not appear to stick to themselves with great strength. The real test is to use a GAUSS meter."