we are the biggest producer for this product in China, our production capacity is 10000mts per year,was founded in 1983the first SPEC1: content:98%min.moisture:0.5%max.SPEC2: content:99%min.moisture:0.3%max.sulfate:0.01%max.Fe: 0.005%max.SPEC3:content:99%min.moisture:0.3%max.sulfate:0.003%max.Fe: 0.003%max.Residue after ignition:0.02%max.heavy metal:0.001%max. hydroxylamine hcl