ISO D Die Spring, Ultra Strong Duty, Color Gray, Chrome Silicone Alloy Steel, Finish Powder Coated, Overall Length 6 In., Outside Dia. 1-1/4 In., End Type Closed & Ground, For Hole Size 1-1/4 In., For Rod Size 5/8 In., Spring Rate 2329.7 lb./in., Meets/Exceeds ISO10243