ISO D Die Spring, Medium Duty, Color Blue, Chrome Silicone Alloy Steel, Finish Powder Coat, Overall Length 3-1/2 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 508.8 lb./in., Meets/Exceeds ISO10243