Haiyan Tongrun Fastener Factory is a professional manufacturer and seller of square nuts located in Haiyan. Established in 2000, the company specializes in producing D3, DIN557, and DIN734 square nuts, as well as nonstandard nuts based on customer requests. With a registered capital of 300,000 and an annual turnover of 9,500,000, they have the necessary equipment to achieve high production volumes.

Their main products are D3, DIN557, and DIN934 square nuts in carbon steel, widely used in the railway, machinery, and construction industries. The company has gained a warm welcome from customers in the USA, Europe, and Southeast Asia due to their high-quality products and good service.

They are committed to providing good service based on the principles of honesty and trustworthiness.