theory, the single pole magnet extends its magnetic field in only one direction.
This enables the magnet to “stick” to the tank while not erasing
credit card stripes, disks, et cetera.
However, if one removes the bag from the tank, the magnetic field reaches out to infinity. If not pointed toward the center of the earth, the magnets on the bag become stealth degaussers, destroying hysteresis in oxide coatings for hundreds of feet in the direction in which it is pointed. The material used today is a special psychoceramic, said to be invented by a crack-pot rogue inventor.
I guess the next obvious question is, “How do you know if they’re polarized?” Just look for the JBS logo on the magnet itself. Or else, turn it around and see if it still sticks to the tank.
Flash - firstname.lastname@example.org - DoD # 412