Springs (also called tension springs, or simply tension springs) are helical springs that are subjected to axial tension, [ Tension springs are generally made of materials with a round cross-section. When not under load, the coils of an extension spring are generally tightened together with no gap between the coils. Tension springs are helical springs subjected to axial tension, and their hooks are 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 circular cross-section material, and are usually tightly packed without gaps between coils when they are not subjected to loads. Work, used 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. Extension springs work in reverse to compression springs. While compression springs work in reverse when compressed, extension springs work in reverse when extended or pulled apart. When the ends of an extension spring are pulled apart, the spring tries to pull them back together. Like compression springs, extension springs absorb and store energy. But unlike compression springs, most extension springs are usually under some degree of tension, even without any load. This initial tension determines how tightly the extension spring is coiled without any load.