1 1/2" id

This neodymium countersunk magnet is made of super strong N42 NdFeB (NIB) material, coated with Nickel (Ni+Cu+Ni triple layers). The dimension of this Big neodymium magnet is 3″ od x 1 1/2″ id x 1/4″ thick, magnetized Through Thickness. Its individual pull force is approximately 56.72lbs.