This standard is a core component of the rubber hardness measurement methodology system. It specifies in detail four methods for measuring the standard hardness of rubber on flat surfaces and four additional methods for measuring the apparent hardness of rubber on curved surfaces, all expressed in terms of International Rubber Hardness Degrees (IRHD). The core principle involves precisely measuring a material's resistance to indentation by stipulating spherical indenters of different sizes and applying varying indentation forces, making it applicable across a broad hardness range from 10 IRHD to 100 IRHD. Unlike the commonly used portable Shore durometers, this standard primarily describes the International Rubber Hardness Tester used under laboratory conditions. It is identical to the international standard ISO 48-2:2018 and aims to provide an authoritative testing method with high precision and excellent repeatability for quality control of rubber products.