... 20-25days ISO16949While we make a full range of trailer parts include conventional leaf spring and parabolic leaf ... exported to overseas throughout over 30 countries terms of Asia, Mid-east, Euro and North-America etc ... produce over 25000tons per year with general capacity.The raw material we use SUP7,SUP9,SUP9A,SUP11, ... that continuous improvement is a way of life. semi-trailer leaf spring TRA262