ASTM D5420-21 is a standard test method used to evaluate the impact performance of flat hard plastic specimens, utilizing the Drop Weight Impact (Gardner Impact) method. This method tests the impact resistance of a material by striking a firing pin that has fallen from different heights to determine the failure of the material at specific energies. This test method is suitable for a variety of industrial application scenarios that require an understanding of how a material behaves under impact, using the same equipment used in the ASTM D2794 method for measuring coating resistance to impact. ASTM D5420 emphasizes the application of different firing pin diameters and sample support plate geometries in testing to simulate the material performance under a variety of real-world use conditions.