Prime-Line products has been supplying repair and replacement parts for windows and doors. This extension spring from Prime-Line is constructed from 0.091-gauge, heat-tempered, spring steel wire plated in a bright nickel finish. It offers superior strength and long lasting tension. This spring features a single loop, closed end design. This type of spring can be used on toys, equipment, tools and for a variety of other household applications. Made from durable 0.091 diameter wireMaximum weight capacity is 31.3 poundsGeneral use spring for toys equipment tools etc.