GB/T 39693.5-2025 is the fifth part of the series of standards for the determination of Hardness of vulcanized rubber or thermal plasticity rubber. The special project specifies the press-in Hardness measurement method of portable rubber international hardness gauge (IRHD). The standard clarifies the test principle, instrument requirements, operation steps and results of the method. It is suitable for hardness testing of two types of rubber in field or rapid testing scenarios. It can unify portable testing standards and ensure data conformity. It provides reliable technical support for mass rapid screening and application adaptation of rubber products.