1. C type Clamp Jaws: Sturdy and durable, made of 1.7 millimeter thick heat treated steel, black oxidized, not easily bent or deformed when compressed. The two ends of the C type clamp are aligned in a standard straight line, not easily slipping during use. 2. Toolbox Storage: Comes with 5 adapters for springs of different diameters to ensure correct spring installation and safe and easy spring compression. The whole set of 10 tools is neatly packaged in a box for easy storage and transportation. 3. Heavy duty Steel Structure: Sturdy and durable. The components are treated with an oxidation coating, rust and corrosion resistant. Each part has a smooth surface, ensuring easy use even under compression conditions. 4. Function: Equipped with 5 adapters of different sizes, suitable for springs of different diameters on most cylinder heads. Can accurately adjust the spring position for easy compression operation.