Century Spring warehouses the largest inventory of high-grade extension springs in the world. Extension springs are designed to absorb and store energy as well as create a resistance to a pulling force. It is initial tension that determines how tightly together an extension spring is coiled. This initial tension can be manipulated to achieve the load requirements of your particular application. All Century extension springs are wound with an initial tension force which offers a small deflection load for secure installation "holding". The initial tension is equal to the minimum force required to separate adjacent coils. Each spring is of the constant diameter type with a variety of hook/loop styles. Spring Anchors are also available.