Prime-Line products has been supplying repair and replacement parts for windows and doors since 1978. This extension spring from Prime-Line is constructed from 0.105-gauge, heat-tempered, spring steel wire plated in a bright nickel finish. It offers superior strength and long lasting tension. This spring f measures 12 inch length by 1 inch diameter. General use spring for toys equipment toolsNickel plated finishOutside diameter is 1 inchEnd type is single loop, openMaximum weight capacity is 35.4 pounds