You are now seeing this is a rubber material belonging to the magnetic ring, the size is larger, outer diameter 179mm, hole 119mm, thickness 4.3mm, thickness magnetization, no coating, weak magnetic, mainly used for advertising, display racks and other places that do not require strong magnetism, cheap, interested in sending inquiries for further communication.
Rubber Magnetic Science;
Difference between isotropy and anisotropy of rubber magnets