The D-ring is also called a fixed lashing ring. The implementation standard is GB/T 16856-1997, and the models are CA-36, CA-42, CA-50. Representation: The D-ring with a breaking of 490KN is marked as: fixed lashing ring CA-50 GB/T 16856-1997. The material is alloy steel, the grade is 40Cr, 35CrMo, 425CrMo, and the standard number of the material is GB 3077 88.