Guangzhou Naian Auto Part Co.,Ltd is the manufaturer forconventiional leaf spring,parabolic leaf spring, z-type leafspirng, heavy duty trailer leaf spring. We have more than 10 yearsexperiene in the field. All our leaf spring matearial are tested.The materil could be SUP7, SUP9, SUP11, it depends on the yourdemands. We have our onw design engineers to design new spring foryou.