Tension springs are helical springs subjected to axial tension, and their hooks are available in the form of side hooks, long hooks, English hooks, German hooks, semi-circular hooks, duckbill hooks, and so on. The hooks are used to ensure that the source of tension in tension springs is generally made of spring steel with a round cross-section material, and are not subjected to loads. When not under load, the coils of an extension spring are generally tightened without gaps, and work by using the rebound force (tension) after stretching to control the movement of the machine, store energy, measure the size of the force, etc. Most extension springs are usually under a certain degree of tension, even in the absence of any load. This initial tension determines how tightly the extension spring is coiled without any load. Tension springs are widely used in medical respiratory equipment, motion control, medical mobility equipment, hand tools, home care equipment, vibration damping, pump springs, mechanical and electronic protective hardware, fluid control valves, mechanical aerospace components, actuators, switchgear machines, and instrumentation. The materials include stainless steel, piano steel, high carbon steel, phosphor bronze, and oil tempered alloy spring steel. The use of stretching the resilience (tensile) work, used to control the movement of the machine parts, storage energy, measuring the size of the force, etc., widely used in machinery, instrumentation. Tension springs are helical springs subjected to axial tension, and their hooks are available in the form of side groove tension springs, long hook tension springs, English hook tension springs, German hook tension springs, semi-circular hook tension springs, duckbill hook tension springs and so on, and the "hooks" are used to ensure that the source of the tension of the tension spring. Generally made of spring steel with a round cross-section material, when not subjected to loads, the coils of the spring and the coils are generally and tightly no gap between the use of stretch after the rebound force of the work to control the movement of the machine parts, storage energy, measuring force size, etc., the majority of extension springs are usually in a certain degree of tension, even if there is no any load case. This initial tension determines how tightly the extension spring is coiled without any load.