ISO D Die Spring, Ultra Strong Duty, Color Gray, Chrome Silicone Alloy Steel, Finish Powder Coated, Overall Length 4-1/2 In., Outside Dia. 1-1/2 In., End Type Closed & Ground, For Hole Size 1-1/2 In., For Rod Size 3/4 In., Spring Rate 3877.1 lb./in., Meets/Exceeds ISO10243