These countersunk ring magnets are 0.500 inch (12.7mm) outside diameter, 0.150 inch (3.8mm) inside diameter and 0.125 inch (3.2mm) thick. They are magnetized through the thickness. They are composed of grade 40 neodymium iron boron magnetic material and are plated in nickel-copper-nickel for a shiny corrosion resistant finish. Their individual pull force is approximately 3 lbs. Maximum working temperature is 176 F (80 C).
CHOKING HAZARD -- Small parts. Not for children under 3 yrs.