The constant force spring can be used to counterbalance items, such as windows (known in the window industry as coil balance springs), doors, display racks and trays. It can also be used as a return or retracting mechanism wherein the constant force spring will provide a smooth, even, uniform load through its entire length or travel (deflection). Travel (extension, deflection) is limited only by the length of material in the spring. Load is a function of material width, thickness and coil diameter. Increased loads can be obtained by using two or more constant force springs interwound or in tandem or in other configurations.