They are ISO and IEC, UL certified. High quality material is chosen to guarantee its excellent performance. For example, Pb-Ca-Tin-Al lead alloy optimized for high corrosion resistance, highly porous glass micro fiber separator and lead with its purity up to 99.999% are used. Furthermore, strict quality control process and automatic production line are carried out in our factory so that we are proud that we can control acid density to 1.28~1.30kg/l, while higher acid density such as 1.33~1.35 can be very harmful to the long service life of battery, while many competitor make such high acid density battery for low price without quality assurance.