semi trailer steel leaf spring 1.Thickness: 6~50 mm 2.Material: SUP6, SUP9, SUP9A, SUP11A and so on 3.Delivery time: 20 days We manufacture and sell & export leaf spring used on trailer and truck, including multi leaf spring, z type leaf spring used on the suspension.1) type: straight leaf spring, z type leaf spring, multi leaf spring , return spring, brake spring, adjuster spring etc.2) Material ...