I really don't know about this, but the regular manufacturers generally include Shanghai XXXX (Shanghai manufacturer), Guangdong XXXX (Guangdong manufacturer), Sichuan XXXX and so on. Or Shanghai XXXX, Guangdong XXXX, etc. , can narrow down the scope. If not, it is probably not a formal certified product.

Stainless steel hardening refers to hard stainless steel, followed by porcelain. Is it domestic hard stainless steel?

My calipers are only hardened with stainless steel.