From bead to rod: Comparison of theories by measuring translational drag coefficients of micron-sized magnetic bead-chains in Stokes flow | PLOS ONE
Neodymium Ring Magnets | Strong Rare-Earth Magnets
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Square metal tubes with magnets glued in one end that apparently stick to square bases. One side of tube is open/hollow. : r/whatisthisthing
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Source N42 Neodymium Magnets Tube Hollow Magnet on m.alibaba.com
Tube Magnets - Magnetic Tube - Greenwood Magnetics
Tube Magnets - Neodymium Magnets - SuperMagnetMan
12p N52 Diametrically Magnet Ring Tube Diameter 8x3.05x20 Mm Precision Ndfeb High Temp. Neodymium Permanent Rare Earth Magnetic - Magnetic Materials - AliExpress