Amazon.com: Master Magnetics COW-RUM5CX3BX Cow Magnet, Ultimate Heavy Duty Ru-Master 5, Steel Ring and Ferrite, 0.75" Diameter, 3.375" Length, Black and Silver (Pack of 3) : Industrial & Scientific
United Scientific Supplies MGTCOW-A Cow Magnet, Alnico, 1.25 cm Diameter: Amazon.com: Industrial & Scientific
Cow Magnet, Alnico, 3.5" x .5" - Arbor Scientific
Ringed Ferrite Cow Magnet Leedstone
Cow Magnet ~ Heavy Duty
Informative & Interesting on Twitter: "Cows are fed magnets that stay in their stomach for life to collect metal objects like nails or barbed wire that the cow will occasionally eat, thus
3" X 1/2" ALNICO COW MAGNET
Master Magnetics 07238 Ru-Master 5 Heavy Duty Cow Magnet, 3/4" x 3-3/8" - Walmart.com