Features: Make of highly elastic and fatigue resistant spring steel material, ensuring long terms performances and resistance to wear and tear. With double hook, which can be better fixed on the mechanical equipment to ensure the stable operation of the equipment. These tension springs offer consistent and stable stretching force, great for applications requiring controlled tension or resistance. Tension Spring can be used in many occasions, such as production and assembly, experiment, research and development, maintenance,Home Repair. Package includes: 12pcs Extension springs with hook ends. Offering great tension and flexibility, these springs is builted to bear heavy duty use. Specifications: Materials: Stainless steel wire Length: about 16.50cm/6.5inch Outer diameter: about 9.53mm/0.37inch Wire diameter: about 1.2mm/0.047inch Package Includes: 12Pcs Extension Spring note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to difference between different monitors, the picture may not reflect the actual color.