Music Wire Extension Spring, Steel, Inch, 1.25" OD, 0.115" Wire Size, 4.5" Free Length, 8.84" Extended Length, 44.03 lbs Load Capacity, 9.2 lbs/in Spring Rate (Pack of 10) Highly magnetic steel music wire per ASTM A228 for greater strength than stainless steel Full twist loop ends for secure fastening Load capacity of 44.03 pounds Maximum operating temperature of 250 degrees F (121 degrees C) Dry to the touch oil finish for added corrosion resistance