The original Ultimate Heavy-Duty, Ru-Master 5 cow magnet, Master Magnetics' patent #5128644 has helped dairy farmers and veterinarians to prevent Hardware Disease in cattle since 1992 0.75" diameter, 3.375" length (19.05 mm diameter, 85.725 mm length) with stainless steel connector rod through the core and rounded steel end caps securely fastened. No plastic parts Powerful Ferrite (Ceramic) magnets and steel rings divided into segments create superior strength, consistent pulling force along length, and alignment of tramp iron parallel to magnet Rounder ends and slightly heavier than other cow magnets. These qualities make it easier for the magnet to travel to the stomach and stay there Administer with ordinary balling gun. Magnet does not lose power. One magnet works for the life of the cow!