日本采购需求：镀锌管、无缝管、GI管、镀锌钢管、ERW管、无缝管

I am looking to place an order for custom square iron blanks that meet specific requirements. It would be great if you could provide detailed information on the available grades of iron, dimensions, thickness options, and surface finishes that you offer. Additionally, please let me know about the production lead times and any minimum order quantities that I should be aware of. I'm particularly interested in understanding your capabilities in terms of customization and the potential for bulk orders. If you have any samples or previous work that showcases your quality, please share that as well. I look forward to your prompt response so we can discuss this further and move towards finalizing the order.