This button magnet is made of Alnico five magnet material. It is a cylindrical magnet with poles in one plane and has a maximum pull of 4.2 pounds. It has a stability temperature of 1,022℉, a hole diameter of 0.188 inches, and a tap size of 0.22 inches to 0.34 inches. It is made of Alnico five magnet material. It measures 1/2 length x 1/2 width x 3/8 height x 3/4 inches diameter.