General Tools and Instruments Alnico magnets featuring aluminum nickel and cobal alloy are built for heavy duty use and will not naturally demagnetize over time. The strong magnetic pull of these industrial grade magnet makes it perfect for lifting holding sorting clamping or retrieving steel or iron parts. Alnico magnets will retain their magnetic force indefinitely; removable keepers insure a long life and optimum performance. Button shaped magnets have almost unlimited applications; A center hole on this magnet provides easy fastening options. This magnet has a diameter of 3/4 inch and stands 1/2 inch tall with a cored hole of 1/8 inch; Pulls up to 4 lbs.