Describe：

JIS F2804-1976 is a Japanese Industrial Standard (JIS) specification that pertains to ship cross bitts, which are fixtures used on ships for mooring purposes. 

These bitts are designed to provide a strong point for securing mooring lines, ropes, or cables, helping to keep the vessel stable when it's berthed or anchored. The specification likely includes details such as dimensions, materials, manufacturing processes, and performance requirements for these bitts to ensure they meet safety and quality standards for marine use.

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