Tonic Studios-Tim Holtz: Stamping Platform Replacement Magnets. Replacement magnets for use with the Tim Holtz Stamp Platform. This 4×4.875 inch package contains two high magnetic strength neodymium magnets. WARNING: Neodymium magnets are very brittle. Handle with care to avoid personal injury and damage to magnets. Choking and pinching hazard. Keep away from children. Strong magnets can be harmful to pacemakers. Imported.