This rectangular cow magnet is made of Ceramic 5 (Strontium Ferrite) magnet material. Its special magnetization pattern causes nails and other sharp metal objects line up along the length of the magnet where they are no longer a danger to the cow. The epoxy coating is gentle on the cow and helps protect the magnet from chipping. Rounded corners ensure safe and easy passage to the reticulum. Measures .5" x .75" x 2.75" long.