Extension Spring, Ultra Precision, High Carbon Steel, Plain, End Type Full Twist Loops, Overall Length 4 In, Outside Dia 0.500 In, Wire Dia 0.055 In, Load 13.10 Lbs, Deflection @ Load 4.38 In, Initial Tension 1.20 Lbs, Spring Rate 2.70 Lbs/In, Meets/Exceeds ASTM A228 and AMS 5112, Package 3