I really don’t know about this, but for regular manufacturers, the ruler body usually has the Shanghai-made XXXX number (manufacturer in Shanghai), the Yue-liang number XXXXX (the Guangdong manufacturer), the Sichuan-liang number XXXXX, etc. or the Shanghai-made XXXXX Number, Guangdong-made XXXXX number, etc. You can narrow down the scope through this. If you don’t even have this, it is probably not a formally certified product.

Stainless hardened means hard stainless steel, followed by china. Is it domestically produced hard stainless steel?

My calipers are only stainless hardened.