Tempered film is a common surface treatment technology that heats the glass material to a high temperature and then cools it quickly to form compressive stress on the surface, thereby increasing its hardness and strength. Specifically, tempered films can be divided into different hardness levels, and the common ones are as follows:

1. 3H level: This hardness level of tempered film is relatively soft and is mainly used for ordinary household electronic products or low-demand display protection.

2. Grade 4H: Grade 4H tempered film is harder than grade 3H and can provide better anti-scratch performance. It is suitable for devices with high requirements for screen anti-scratch.

3. 5H grade: 5H grade tempered film has higher hardness and can better resist scratches from external objects. It is suitable for devices with strict screen protection requirements, such as smartphones, tablets, etc.

4. Grade 9H: Grade 9H is the highest hardness grade of tempered film currently on the market. It can effectively resist scratches from most sharp objects and is a common choice for smartphones and other high-end electronic devices.