What are Zuo Tiannu's chrome-free tanned health shoes?

Simply put, chrome-free tanned healthy shoes can directly contact the skin. "Chrome-free tanning" is a tanning method of leather treated with organophosphorus salts. Tested by three authoritative organizations SGS (Swiss Standard), STR (Sheng Bang, USA) and IQTC (Guangdong Import and Export Inspection), hexavalent chromium and azoarylamine were not detected, and the formaldehyde content was less than 75mg/kg, which met the national Class B standard and could directly contact the skin. At present, the leather technology on the market is generally qualified when it reaches the C standard, but it is not suitable for direct contact with the skin.